Paul Lagassé, May 2026
If you search the Internet to find out how much the Mason-Dixon survey cost, you will find several different answers. One common one is $75,000, which is found on the website for Encyclopaedia Britannica,
The line was completed in 1768 at a cost of $75,000.[1]
Wikipedia offers a different figure,
It cost the Calverts of Maryland and the Penns of Pennsylvania £3,512 9/- (equivalent to £505,009 in 2025) to have 244 miles (393 km)[2] surveyed with such accuracy.[3]
American Heritage’s website offers two numbers, without clarifying to what degree the first sum includes the second,
For both proprietors it was an expensive undertaking, costing in all the equivalent of at least $100,000 in modern currency.
On September 11, 1768, four years and ten months after their arrival, the English geodesists sailed from New York for Falmouth. In London, on November 11, they submitted a final bill for £3,512/9 s., including passage money.[4]
This information is from an article from 1964 by William Swindler, as the webpage notes, but an archived version of the same article indicates that the authors are A. Hughlett Mason and William F. Swindler (the former edited The Journal of Charles Mason and Jeremiah Dixon [1969]).[5]
The Mason-Dixon Line Preservation Partnership website has a short paper on the topic, Robert Bechtol’s “Surveying Mason and Dixon’s Line – What did it cost?”[6] This last is an attempt express the survey costs in 2002 dollars. Bechtol gives the costs, as does American Heritage, as two numbers,
Their reported combined total earnings for five years in America were 3,516.45 pounds x $122.62/pound = $431,187….
Penn’s expenses for running the line from 1760 to 1768 are documented to be 12,825.18 pounds x $122.62/pound = $1,572,623.
We can assume Lord Baltimore's expenses were at least the same, so $1,572,623 x 2 = $3,145,247, the estimated total expenses for the Proprietors.
Bechtol doesn’t clarify to what degree the first sum includes the second. He does note his sources and methodology for updating the costs:
A study done for David Dutcher, Chief Historian, National Park Service, Philadelphia in 1990 showed a conversion of one Pound (1776) equals $88.20 (1990). Another study done about the same time by a different agency using different criteria showed one pound (1776) equals $89.94 (1990), in remarkably good agreement. For our purpose, we will use the average of these two, or one pound equals $89.07(1990) to convert to 2002 dollars. We have allowed an average of 2.7% for the annual increase in the Consumer Price Index over the twelve-year span to get $89.07/pound x (1.027)12 =122.62/pound in 2002 dollars.
He also lists Report of the Resurvey of the Maryland-Pennsylvania Boundary, Part of the Mason and Dixon Line, pp. 353–355 (Baltimore: Maryland Geological Survey, 1907), as a reference. The specified pages contain information on the costs of the survey of the boundary lines that Mason and Dixon marked.
The Resurvey (as I shall refer to it) is invaluable to gaining some insight concerning the smorgasbord of cost figures above (and others out there and not quoted). A 400-page work, it is, despite its title, largely concerned with the history of the territorial conflict between the Lords Baltimore and the Penns and the surveys of the boundaries between their colonies and the states that succeeded the colonies. Its largest section, somewhat short of half of the 400 pages, is devoted to an annotated bibliography of manuscript sources (or copies of those sources) for the conflict and the boundary surveys, from 1606 to 1852. Many sources are given a brief description and/or an abstract. (The quotations from the Resurvey below are given in full, along with other mentions of various costs during 1760 to 1770, at the end of this document in Appendix A.)
Turning to the Resurvey pages noted above, we find several references to invoices from Mason and Dixon. One of them cross-references an earlier entry on page 340 for July 20, 1763, which is for the surveyors’ contract.
Contract [rough draft] between Thomas Penn, Richard Penn, Lord Baltimore proprietaries [London] and two mathematicians [spaces left blank for names], agreeing to pay the latter 10 sh. 6 d. each from the 26th of June, 1763, to the day of their landing in America; £1 1 sh. for each day during the time they are in America and up to their landing again in England; 10 sh. 6 d. extra each day on their return passage and £1 1 sh. for the time necessary to complete the work. Provisions are made as to the time to be allowed for the accomplishment of the work and stipulation that the expense shall be borne proportionately by the proprietaries….
Note. This contract is apparently the draft prepared by the solicitors and may have been used as the “copy” for an engrossed instrument. The date is pencilled in only, at the top of the first page. See Aug. 4, 1763.
August 4, 1763 is on the same page.
Instrument of Reciprocal Agreement between Lord Baltimore and the Penns and Mason and Dixon.…
Abst. Lord Baltimore and the Penns agree to pay traveling expenses and one pound one shilling a day tor services of Mason and Dixon. Mason and Dixon agree to give their best assistance. All bind themselves in penal sum of two hundred pounds for faithful Performance of the Agreement. [Decision to employ Messrs. Mason and Dixon reached 20 June. Agreement as to pay 14 July.[7] See memo, with bill of surveyors. 11 Nov. 1768….]
This outline of how they are to be paid is confirmed by the surveyors’ invoice, which went through several revisions. The final version is not that of November 11, 1768, which states the gross charges before deductions as £3512.9s, but seems to be one that is summarized in a copy dated Feb. [no day filled in], 1769 (Resurvey 355).
Account and Receipt. "The Right Honble Lord Baltimore and The Honble Thos. Penn and Rich. Penn, Esqr. To Charles Mason and Jere Dixon for Wages. London Feb. (?) 1769….
Abst. This seems to be a copy of bill finally agreed upon. The date of the month is not filled in nor are any signatures attached. Compare with Mason and Dixon's bill for a different amount presented Nov. 11, 1768. The period unaccounted for, 26 Dec. 1767 to 21 June 1768 was the time occupied by them in measuring the degree of latitude for the Royal Society. See Commissioners Minutes Aug. 27, 1768.[8] Endorsed "Copy Penn vs. Ld. Baltimore, The mathematicians account and receipt. Ingrossed on the back of the agreement." Total Dr. £3516.9.
26 June 1763 to Nov. 15, 1763, 142 days at 10s. 6d. p. day to each.
15 Nov. 1763 to 26 Dec, 1767, 150 days at £l.ls. to each.
21 June 1768 to 21 July 1768, 30 days at £l.ls. to each,
21 July 1768 to 28 Aug. 1768, 37 days at 10s. 6d. to each.
11 Sept, 1768 to 7 Oct, 1768, 26 days at 10s. 6d. to each,
"For our passage to America and passage hence to England £84. Total credit £10.70s.7d."
"By cash paid said Mason and Dixon before their departure from England £142."
"By cash paid us by the Commissioners in America as appears by our certificates £922.7s.7d."
Unfortunately, the total number of days that they worked on the survey from November 15, 1763 to December 26, 1767 is wrong and is presumably mistranscribed.
The invoice isn’t tallied, but it can be (1 pound = 20 shillings = 240 pence[9]), with the results expressed decimally for ease of summation:
142 days at 10s. 6d. p. day to each = 1420s. 852d. = 1491s. = 74.55 pounds
150 days at £l. ls. to each = £150 150s = 157.5 pounds
30 days at £l. ls. to each = £30 30s = 31.5 pounds
37 days at 10s. 6d. to each = 370s. 222d. = 388.5s. = 19.425 pounds
26 days at 10s. 6d. to each = 260s. 156d. = 273s. = 13.65 pounds
As noted, the second line is clearly incorrect. The total without it is 139.125 pounds. For the invoice to tally correctly, the number of days should be 1502 days, or £1502 1502s. = 1577.1 pounds. This gives a total of 1716.255 pounds each, or 3432.45 pounds total, which plus £84 for transit = 3516.45 pounds decimal = £3516.9s.
From which were deducted the following credits,
"For our passage to America and passage hence to England £84.
Total credit £10.70s.7d."
(I interpret the notation concerning the total credit to mean that the passage for both surveyors to and from Pennsylvania was less than the £84 allowance they were given. However, the above credit is clearly mistranscribed, as the number of shillings should be less than 20—20 shillings equals and would have been recorded as £1, and 70s. should be written as £3.10s.—perhaps the number of shillings should be 10 or 7.)
"By cash paid said Mason and Dixon before their departure from England £142."
"By cash paid us by the Commissioners in America as appears by our certificates £922.7s.7d."
Not included in the above credits but included in an early invoice is
"Bill of exchange drawn upon The Honble Thos. Penn Esqr., when we were at New York, Sept. 10, 1708, £30.00.00" [opposite which Penn ? wrote on the first bill "Dont put in this"] (Resurvey 353)
Finally, the Resurvey (p. 354) indexes another crucial file:
Original vouchers amounting to £12,825.2.1., Pennsylvania currency….
Note. “The vouchers ... are the original receipts given for money expended by the Penn family in running the line between Pennsylvania and Maryland from the year 1760 to 1768….” The equivalent in dollars is said to be $34,200.28. If the Baltimores paid an equal sum the Mason and Dixon line cost over $75000….
Here, in the Resurvey, are the figures that give rise to many of the computations of the costs of the Mason-Dixon survey: The surveyors’ fee of £3516.9. in a 1769 invoice for the years 1763–1768 and two different figures for that fee (£3,512.09.00, which is used by Wikipedia and the American Heritage article, and £3516.19.00) from November 1768, the sum of the Pennsylvania commissioners’ vouchers for the years 1760–1768, and the Resurvey’s conversion of the assumed total expenditures paid by both the Penns and Lord Baltimore in America during 1760–1768.
To obtain a reasonable estimate of the costs of the Mason-Dixon survey, several additional things need to be taken into account.
“To this expense for running the line,” Bechtol notes, “should be added the other large, but unknown expenses incurred by both proprietors during the 80-year long disagreement, e.g. running the line of 1750, the Temporary Line, the Commissioners’ meeting and wages, and the many and large court costs and legal fees from 1692 to 1769. The sum would be considerable.” But these expenses are not our concern here.
So, how much did the work of 1760 to 1768 cost, using the information above?
I do not believe that we can calculate this cost with precision. We will use the inflated cost of goods (the Consumer Price Index) as the basis for the calculations below, because that is the most common way of thinking about this issue, and because it expresses the relative value of the outlays by the proprietors in terms of purchasing power, which seems to be a reasonable way of trying to understand their costs. But it is not the only way to evaluate costs in Mason and Dixon’s time in current dollars (see Appendix B).
Bechtol did his calculations in 2002, so to begin with we must update, or inflate, his 2002 valuation of the pound in Mason and Dixon’s time. What is $122.62 in 2002 worth today?
The Minneapolis Federal Reserve Bank’s Inflation Calculator [10] gives $219.47.
The U.S. Bureau of Labor Statistics CPI Calculator[11] gives $224.37.
The average of the two for 2025 is $221.92. (I used 2025 because that was the date of the latest data available from the Minneapolis Fed site.)
According to the Bank of England’s Inflation Calculator[12] online, 1 pound in 1769 (the year of settlement of Mason and Dixon’s invoice) is worth £159.70 in December 2025. (1 pound in 1776, the year used in Bechtol’s inflated conversions, is worth £143.50 today according to the Bank of England.) According to the MTFX Group’s British Pound to US Dollar Historical Exchange Rates calculator online,[13] 1 pound equaled 1.34476 dollars on December 31, 2025. (The pound has ranged between 1.2 and 1.4 dollars since 2016 according to this website, but was close to 2 dollars at the end of 2007.) This gives an inflated figure of $214.76 at the end of December 2025 for £1 in 1769.
These figures are all relatively close. But because we are dealing in British pounds, I will use the last figure, and because too much “apparent” precision in the valuation gives a false sense of precision to the results, I will round it down to $214. (Most other figures from here on will be rounded down, to continue to undermine any sense of precision.) I also will use the Bureau of Labor Statistics value, $224, which is the greatest of the above, to create a range.
We must also account for the fact that British pounds were worth more than their colonial “equivalents.” Ron Michener’s “Money the American Colonies,”[14] a webpage at the Economic History Association’s EH.net website, says
The units of account in colonial times were pounds, shillings, and pence (1£ = 20s., 1s. = 12d.). These pounds, shillings, and pence, however, were local units, such as New York money, Pennsylvania money, Massachusetts money, or South Carolina money and should not be confused with sterling. To do so is comparable to treating modern Canadian dollars and American dollars as interchangeable simply because they are both called “dollars.” All the local currencies were less valuable than sterling. A Spanish piece of eight, for instance, was worth 4 s. 6 d. sterling at the British mint. The same piece of eight, on the eve of the Revolution, would have been treated as 6 s. in New England, as 8 s. in New York, as 7 s. 6 d. in Philadelphia, and as 32 s. 6 d. in Charleston (McCusker, 1978).[15]
The value of a piece of eight is 54 pence in sterling but 90 pence in Pennsylvania and 96 pence in New York, which suggests that the Pennsylvania pound was worth 0.6 pounds sterling at the time. Using this information to determine the value of Pennsylvania’s currency yields $129 today ($215 x 0.6).
The online site The Continental Line, on its page “How much is that….?”[16] says
We know, for example, that in the fairly stable period of 1766 to 1772, one pound in Pennsylvania currency converts to $43.80 in 1993 U.S. dollars.
Converting $43.80 in 1993 dollars to today’s dollars at the two U.S. inflation websites we used earlier gives us $97.61 at the Minneapolis Fed and $99.53 at the Bureau of Labor Statistics CPI Inflation Calculator. I will use $97 and $129 below, to create a range. Interestingly, this range is greater ($32) than that we are using for the British pound ($10), for which the modern-day value is almost twice as large.
Following Bechtol, “Mason and Dixon were paid 1 pound, 1 shilling per day while in America. 1 pound, 1 shilling [is] 1.05 pounds in decimal form,” so 1.05 x $215 to $224/pound = $225.75 to $235.20 per day as wages, or $225 to $235. However, as was shown above, Pennsylvania currency was worth significantly less in present-day terms. In the colonies, using the value range of $97 to $102 for Pennsylvania pound, the 2025 equivalent of their daily wages would be about $102 to $135 per day. How much they earned per day and in total depends on where they are compensated.
Bechtol doesn’t account for the differences in currencies. If we were to follow him and merely revise his results using our 2025 valuations, “Their reported combined total earnings for five years in America were 3,516.45 pounds” x $215 to $224 pound = $756,036 to $787,684. “Each man was entitled to half of this,” or $378,000 to $393,000 (rounded down). But some of this was paid in advance in England, some in the colonies, and the bulk on their return to England. This figure also doesn’t include £30 from Thomas Penn, as noted above. He said not to include it, and I will follow his advice. But if you want to add it in, the value of the New York currency in pounds sterling would be £16.875 (following Michener above), perhaps around $3,600 to $3,870 today.
The £922.7s.7d that the surveyors received in the colonies and the presumably mistranscribed £10.70s.7d credit should both be deducted from the surveyors’ gross charges of £3,516.9s to determine what they were paid in British currency before leaving England and at settlement in 1769. Using a rounded up £933 as the sum of our necessarily imprecise deduction, the surveyors should have received around £2,583 in all in pounds sterling, or $555,345 to $578,592. In Pennsylvania currency, they received £922, or $89,434 to $118,938. So, in 2025 dollars, they earned about $644,000 to $697,000, or $322,000 to $348,000 each for about 5 years of travel and work, most of it from 4 years 10 weeks of surveying (when they often worked 6 days a week but were paid for 7, and when they weren’t working at all for weeks at a time during some winters).
According to the original receipts given for money expended by the Penn family in running the line between Pennsylvania and Maryland from the year 1760 to 1768, the Penns’ expenses during that time were £12,825.2.1.[17] Bechtol seems to have recalculated these expenses in today’s dollars from British pounds. The £12,825.2.1. was in Pennsylvania currency.
This would suggest that the costs were more like 12,825 Pennsylvania pounds x $97 to $129/Pennsylvania pound = $1,244,025 to $1,654,425 x 2 proprietors, on the assumption the Lord Baltimore’s expenses were similar = $2,488,050 to $3,308,850. (Bechtol calculated this figure as $3,145,247 in 2002, or as much as $5,745,600 in 2025, using $224 as the inflator for the value of the pound sterling in 1769.)
Different colonies had different currencies with different values, but using Pennsylvania pounds to determine the value of Maryland’s incurred colonial expenses is not unreasonable. Michener, in his online article mentioned above, notes that “In the early 1760s, Pennsylvania money was the primary medium of exchange in Maryland.” As this document focuses on payments made during the early to late 1760s, we are not on entirely thin ice.
To the costs for the survey in Pennsylvania currency should be added what Mason and Dixon received in British pounds in England, both before they left for America and in 1769 after they had returned from in the colonies, which totals from $555,345 to $578,592. These expenditures presumably would not have been accounted for in the original receipts in Pennsylvania currency. Using these two sets of figures, the known expenses for marking the boundary lines Mason and Dixon surveyed, starting from 1760, would total in 2025 dollars from $3,043,000 to $3,887,000.
The full cost for Mason and Dixon represents $644,000 to $697,000 of the total spent on the project, or somewhere in the range of 21% to as little as 18% of the survey’s costs. Because some currently unknown amount of the total 1760–1768 survey costs was not expended on Mason and Dixon’s survey, the portion of the expenses incurred in 1763–1768 to employ the two surveyors is actually somewhat larger.
A rough estimate in 2025 dollars of what the survey cost, based on the above, is thus in the neighborhood of from $3 million to $4 million, an admittedly large neighborhood.
I want to return again to what Bechtol sums up with, “To this expense for running the line should be added the other large, but unknown expenses incurred by both proprietors during the 80-year long disagreement, e.g. running the line of 1750, the Temporary Line, the Commissioners’ meeting and wages, and the many and large court costs and legal fees from 1692 to 1769. The sum would be considerable.”
In fact, the tally for the expenses of 1760 to 1768 is still incomplete. None of the figures above include the costs for the instruments, as best as I can tell. Edwin Danson, in “Jeremiah’s Theodolite,”[18] writes:
As far as is known, Mason and Dixon used only three optical instruments in America to survey and set out the complex boundaries that divided Maryland from Pennsylvania (the MasonDixon Line) and from the Three Lower Counties (Delaware). These instruments were all made for [Thomas] Penn by John Bird at his workshops in Court Gardens, off London’s Fleet Street and comprised:
A six-foot radius Zenith Sector for measuring zenith distances of stars for determining latitude
A thirty-three inch transit and equal altitude instrument, the great grandfather of the modern theodolite; and
An 18 inch radius Hadley pattern quadrant….
As precise as possible for their time, these instruments were undoubtedly expensive, but I have not been able to find any information on their cost in the literature that I am familiar with.
And there were some 220 monuments erected on the line, from the Transpeninsular Middle Point north to the location of today’s Tri-State Marker and then 132 miles west, to the foot of Sideling Hill. An unclear number of additional monuments, never erected, were apparently transported to Fort Frederick, Maryland, on the Potomac in Washington County.[19] It’s not clear how many were left there, but based on W. C. Hodgkins’ notes on the stones on the Maryland-Pennsylvania line in the Resurvey (pp. 84– 101), at least 15 unused stones from Washington County were placed by the Resurvey in locations where mile markers were missing or had never been erected. Hodgkins elsewhere states that others were undoubtedly broken up in order to be repurposed: “There were probably more of them than now exists, as there is evidence that some were cut into smaller pieces for building purposes and the number so destroyed may have been considerable.” (Resurvey 71) If you assume that at least 30 stones had been left unused at Fort Frederick that means that the proprietors also paid for the cutting, dressing, carving, and shipping of at least 250 mile markers, a considerable additional expense that was incurred in England and is all but certain not to be accounted for in the Pennsylvania currency receipts.
So it is hard know, from the information on hand, the exact cost in modern terms involved in this survey that happened more than 250 years ago, but it is reasonable to say that it exceeded $3 million in today’s terms, and certainly could have exceeded $4 million, if we take the costs of the instruments and monuments into consideration.
Extensive additional research would further refine the rough approximations above, but it is clear that most figures currently given online for the costs of the Mason-Dixon survey grossly underestimate the costs.
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As noted above, the figure of $75,000 for the cost of the survey (found online at the Britannica and other websites) seems to originate with the Report on the Resurvey of the Maryland-Pennsylvania Boundary, Part of the Mason and Dixon Line, which says on page 354: “the Mason and Dixon line cost over $75000” in 1907 dollars. $75,000 in 1913 (the start date for the inflation calculators) would be around $2.5 million today. That is, interestingly, very close to the lower value for the inflated cost of the Pennsylvania receipts above, based on the value of Pennsylvania, not British, pounds.
Currently, I cannot correlate the American Heritage figure of $100,000 in the February 1964 article with the figures I have above. $75,000 in 1913 is equivalent to more than $225,000 in 1962 (information for 1962, but most likely not 1963, should have been available in time inclusion in the article). If $100,000 is being suggested as each proprietor’s costs, it does make some sense, but the wording of the sentence in which the sum occurs, “For both proprietors it was an expensive undertaking, costing in all the equivalent of at least $100,000 in modern currency” (italics mine), indicates that the combined Baltimore and Penn costs are being discussed. $100,000 does not seem to be an equivalent for the wages Mason and Dixon received, as those are discussed in a separate paragraph, but, if it were, the 1962 CPI valuation would be in the low $80,000s.
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The Report on the Resurvey of the Maryland-Pennsylvania Boundary, Part of the Mason and Dixon Line (1907, printed as the seventh volume of the general reports of the Maryland Geological Survey, 1908) contains the following information on the costs of surveying, from 1760 to 1770, the lines Mason and Dixon marked:
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p. 336 |
1761, Nov. 12 |
Letter. Governor Sharpe to Lord Baltimore. Ms. Copy. Md. Hist. Soc., Sharpe Letterbook IV, p. 216. Pub. Md. Arch., v. 9, pp. 551-552. Abst. Sends map showing what has been done and asks advice as to running a tangent line. Says that Lord Baltimore's share of expense to date is £1000. Suggests that it may be better to have other surveyors run the northern boundary. |
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p. 340 |
1763, July 20 |
Contract [rough draft] between Thomas Penn, Richard Penn, Lord Baltimore proprietaries [London] and two mathematicians [spaces left blank for names], agreeing to pay the latter 10 sh. 6 d. each from the 26th of June, 1763, to the day of their landing in America; £1 1 sh. for each day during the time they are in America and up to their landing again in England; 10 sh. 6 d. extra each day on their return passage and £1 1 sh. for the time necessary to complete the work. Provisions are made as to the time to be allowed for the accomplishment of the work and stipulation that the expense shall be borne proportionately by the proprietaries. Unsigned. 10 p. 5 p. text. Ms. Orig. Pa. Hist. Soc., Penn MSS. "Boundaries." pp. 105. 106. Note. This contract is apparently the draft prepared by the solicitors and may have been used as the “copy” for an engrossed instrument. The date is pencilled in only, at the top of the first page. See Aug. 4, 1763. See also bill rendered, 11 Nov. 1768. |
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p. 341 |
1763, Aug. 4. |
Instrument of Reciprocal Agreement between Lord Baltimore and the Penns and Mason and Dixon. 4 pp. fol. Ms. Copy. Md. Hist. Soc., Calvert Papers, No. 670. Abst. Lord Baltimore and the Penns agree to pay traveling expenses and one pound one shilling a day for services of Mason and Dixon. Mason and Dixon agree to give their best assistance. All bind themselves in penal sum of two hundred pounds for faithful Performance of the Agreement. [Decision to employ Messrs. Mason and Dixon reached 20 June. Agreement as to pay 14 July. See memo, with bill of surveyors. 11 Nov. 1768. Mr. Gilbert Coke's copy.] |
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p. 342 |
1763, Aug. 17 |
Letter. Cecilius Calvert to Governor Sharpe. Ms. Orig. Lenox Lib. Emmet MSS. No. 14485. Abst. Forwards Dr. Bevis’ transit instrument by Mason and Dixon and receipt for £71 paid them. Discusses minutely the new plan of survey by them. |
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p. 345 |
1765, Sept. 12 |
Letter. Charles Mason and Jeremiah Dixon to Joseph Shippen, Jr. 1 p. fol. Ms. Copy. Pa. Hist. Soc., Penn MSS. "Boundaries," p. 114. Cf. Allen. Cat. Penn Papers, No. 64, lot 2. Abst. Copy of report of progress giving observations taken. They are 95 miles from the point of beginning, which was 2 miles to the north of Newark in Newcastle county. The temporary [run in 1739] line was at first half a mile to the southward, and it is now distant from their vista half a mile. The next station will be North mountain. They hope to run far enough this season to determine whether the line will cross the river Potomac or not. Wrote Governor Sharpe a fortnight ago for £400 or £500, but have had no answer. |
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p. 346 |
1766, April 14 |
Letter. Mason and Dixon to Governor Sharpe. Ms. Orig. Md. Hist. Soc., Gilmor Papers, v. 2, p. 3. Pub. Md. Arch., v. 14, p. 298. Latrobe, Mason and Dixon line, p. 45. Abst. Report that Penns have paid £615 more than Lord Baltimore and ask for £600-£700. |
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p. 349 |
1767, Feb. 9 |
Letter. Governor Horatio Sharpe to Governor Penn. Pub. Pa. Arch., ser. 1, v. 4, p. 262. Abst. Since Sir William Johnson cannot expect at an expense of £500 to get an answer from the Indians in accordance with the commissioners agreement at the last meeting and as he seems very doubtful whether he will be able to prevail upon them now to give their consent to dividing lines being continued to the westermost [sic] limits of Pennsylvania nevertheless if it is thought best that immediate application be made to the Indians, will direct Lord Baltimore's agent to defray one-half of the expense. Should Sir William be apprehensive that the Indians, will be averse to complying with the request which the commissioners agreed should be made, is not in favor of his making any application at all. |
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p. 352 |
1768, Aug. 26 |
Bill. Moses McClean, Steward, to Surveyors Mason and Dixon. Cf. Aug. 26, Minutes Commiss., 1768. Also 1770 Dec. 24 Joseph Shippen's accounting to Penns. |
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p. 353 |
1768, Nov. 11 |
Letter. Charles Mason and Jeremiah Dixon to Thomas Penn. Ms. Orig. Pa. Hist. Soc., Penn MSS. "Boundaries," p. 117. Cf. Allen, Cat. Penn Papers, No. 64. Abst. Asking appointment "to settle our Affairs" any day except the 15th inst. when they have an engagement at the Royal Observatory on business for the Royal Society, and enclosing bills amounting to £3512.09.00. less £1098.10.07. Also, corrected bill omitting item "Bill of exchange drawn upon The Honble Thos. Penn Esqr., when we were at New York, Sept. 10, 1768, £30.00.00" [opposite which Penn ? wrote on the first bill "Dont put in this"]. |
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1768 |
Bill of Charles Mason and Jeremiah Dixon against The Right Honble Lord Baltimore and The Honble Thos. Penn and Richd Penn, Esqrs., Drs. For Wages June 26, 1763-Oct. 7, 1768. "For our passage to America and passage hence to England (£84). Total, £3516.19.00." Ms. Copy. Pa. Hist. Soc., Penn MSS. "Boundaries," p. 117. Cf. Allen, Cat. Penn Papers, No. 64, etc. Amount less by £4.10. Ms. Copy. Mr. Gilbert Cope's library, West Chester, Pa. Cf. Contract with surveyors, 4 Aug. 1763. |
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p. 354 |
1768 |
Pennsylvania Commissioners. "An account of the attendance of the Commissioners of the honorable proprietors of Pennsylvania, in the survey for running the boundary lines between this province and the province of Maryland." 3 p. fol. Ms. Orig. Pa. Hist. Soc., Penn MSS. "Boundaries," p. 116. Abst. James Hamilton, 75 days (Nov. 1760-May 1764); William Allen, 77 (Nov. 1760-Nov. 1768); Richard Peters, 126 (Nov. 1760-August 1768); Benjamin Chew, 179 (Nov. l760-Nov. 1768); Edward Shippen, Jr., 55 (Nov. 1764-Nov. 1768); Thomas Willing, 80 (Nov. 1764-Nov. 1768); William Coleman, 38 (Nov. 1761-Nov. 1763); Lynford Lardner, 37 (Nov. 1760-June 1761); Ryves Holt, 30 (Dec. 1760-Oct. 1761); Total 697 days, total cost £731.17. Richard's share ⅓, Thos. Penn ⅔”[20] |
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1768 |
Commissioners and others. [Receipts given for monies expended by the Penn family in running the line between Pennsylvania and Maryland, 1760-1768.] Original vouchers amounting to £12,825.2.1., Pennsylvania currency. Ms. Orig. Amer. Philos. Soc., Phila. Note. “The vouchers attached are the original receipts given for money expended by the Penn family in running the line between Pennsylvania and Maryland from the year 1760 to 1768. They were preserved among bills and accounts from which they were selected which came into my possession through one of the descendants of Edmund Physick, who during his lifetime was Receiver General for the Penns. Philada, 1st mo. 9th, 1844, Geo. M. Justice.” The equivalent in dollars is said to be $34,200.28. If the Baltimores paid an equal sum the Mason and Dixon line cost over $75000 and the controversy cost this sum added to all the other expenses like the running of the line of 1750, the Temporary Line, the commission meetings under the agreement of 1732, and the court and counsel charges from 1682 to 1769, a period of 87 years. |
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1768, July 2 |
Map. Mason and Dixon. A plan of the boundary lines…. Note. Sept. 3, 1768, to do., paid James Smither for engraving the survey of the boundary lines, £12.00.00. . . . Paid Robert Kennedy, for papers and printing, etc, £20.00.00. Entry in Joseph Shippen’s account book, Penn MSS. “Boundaries,” Pa. Hist. Soc. |
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p. 355 |
1769 |
Account and Receipt. "The Right Honble Lord Baltimore and The Honble Thos. Penn and Rich. Penn, Esqr. To Charles Mason and Jere Dixon for Wages. London Feb. (?) 1769. 2 p. fol. ms. Pages. Ms. Orig. Pa. Hist. Soc., Misc. Papers, Penn and Baltimore-Penn Family, 1768-1884. page 1. Ms. Copy. Md. Hist. Soc., Calvert Papers. No. 1026. Abst. This seems to be a copy of bill finally agreed upon. The date of the month is not filled in nor are any signatures attached. Compare with Mason and Dixon's bill for a different amount presented Nov. 11, 1768. The period unaccounted for, 26 Dec. 1767 to 21 June 1768 was the time occupied by them in measuring the degree of latitude for the Royal Society. See Commissioners Minutes Aug. 27, 1768. Endorsed "Copy Penn vs. Ld. Baltimore, The mathematicians account and receipt. Ingrossed on the back of the agreement." Total Dr. £3516.9. 26 June 1763 to Nov. 15, 1763, 142 days at 10s. 6d. p. day to each. 15 Nov. 1763 to 26 Dec, 1767, 150 days at £l. ls. to each. 21 June 1768 to 21 July 1768, 30 days at £l. ls. to each, 21 July 1768 to 28 Aug. 1768, 37 days at 10s. 6d. to each, 11 Sept, 1768 to 7 Oct, 1768, 26 days at 10s. 6d. to each, "For our passage to America and passage hence to England £84. Total credit £10.70s.7d." "By cash paid said Mason and Dixon before their departure from England £142." "By cash paid us by the Commissioners in America as appears by our certificates £922.7s.7d." Cf. Minutes of Commiss., 27 Aug. 1768 (under 9 Nov., 1768). |
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1769, Feb 24 |
Receipt by Mason and Dixon of Lord Baltimore's moiety. Ms. Copy. Md. Hist. Soc., Calvert Papers, No. 1027. |
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p. 356 |
1770, Dec. 24 |
Accounts. Joseph Shippen with The Honble Proprietaries of Penna monies disbursed by Joseph Shippen, junr for the services of the comss. . . . and surveyors . . . appointed . . . for running the lines between Maryland and Pennsylvania." 1763. 32 p. O. Ms. Orig. Pa. Hist. Soc., MSS. Mason and Dixon survey. Note. Bound in volume entitled “Ms. of Mason and Dixon surveys, 176368. Begins Nov. 3. 1763; ends December 24, 1770. (Includes all expenses of the commissioners, surveyors and Indian escorts, "for riding Express” with letters, for transportation and erection of boundary stones).[21] |
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It is possible that the earnings and costs above are more misleading than I have suggested. In the online article “Defining Measures of Worth: Most Are Better Than CPI,” Samuel H. Williamson and Louis P. Cain write,
In 1931, the average accountant earned $2,250 in 1931 dollars. If you use the CPI to inflate that figure to 2021 dollars, you get a “real” wage of $40,000. Given the median wage of accountants in 2021 was $77,250 (BLS), use of the CPI alone results in a significant underestimate. A different conclusion would be reached if we compare this to the “average household expenditure” (AHE) as measured by the BLS Consumer Expenditure Survey; $2,250 was 1.43 times the AHE for 1931. If one multiplies 1.43 times the AHE for 2021, the relative value of an accountant’s salary is $95,000. $2,250 in 1931 was 50% more than a full time, 60 hour a week production worker would have earned. If the ratio of unskilled wages in 2021 to 1931 is used, the relative value of an accountant’s salary is over $131,000. Similarly, using real GDP per capita yields $250,000 and just GDP leads to a relative salary of over $668,000. Given the wide range of these values, a case can be made for reporting more than one comparator.[22]
The calculator that the Measuring Worth website has for the purchasing power of British pounds (https://www.measuringworth.com/calculators/ppoweruk/) offers the following valuations for £3516.9s. in 2024 (the most recent date available):
In 2024, the relative value of £3,516 9s 0d from 1769 ranges from £619,500.00 to £76,450,000.00.
A simple Purchasing Power Calculator would say the relative value is £658,200.00. This answer is obtained by multiplying £3,516.45 by the percentage increase in the RPI from 1769 to 2024.
This may not be the best answer.
The best measure of the relative value over time depends on if you are interested in comparing the cost or value of a Commodity , Income or Wealth , or a Project . For more discussion on how to pick the best measure, consult the Tutorials.
If you want to compare the value of a £3,516 9s 0d Commodity in 1769 there are four choices. In 2024 the relative:
real price of that commodity is £658,200.00
labour value of that commodity is £8,355,000.00
income value of that commodity is £9,402,000.00
economic share of that commodity is £76,450,000.00If you want to compare the value of a £3,516 9s 0d Income or Wealth , in 1769 there are four choices. In 2024 the relative:
real wage or real wealth value of that income or wealth is £658,200.00
labour earnings of that income or wealth is £8,355,000.00
relative income value of that income or wealth is £9,402,000.00
relative output value of that income or wealth is £76,450,000.00If you want to compare the value of a £3,516 9s 0d Project in 1769 there are three choices. In 2024 the relative:
real cost of that project is £619,500.00
labour cost of that project is £8,355,000.00
economic cost of that project is £76,450,000.00
According to the MTFX Group’s British Pound to US Dollar Historical Exchange Rates calculator (noted above), the value of the pound relative to the dollar at the end of 2024 was 1.25489, which was close to its lowest relative value during the decade that ended in 2025. The lowest value above, £619,500.00, which is for the real cost of a 1769 Project (an investment or government expenditure) in 2024, would be equivalent to $777,460.
Unsurprisingly, this is not that different from the result you would get if you used Bechtol’s approach and determined the value of what Mason and Dixon were paid only in British pounds. Perhaps, from the point of view of the proprietors in England in the 1760s, Mason and Dixon’s wages seemed to be a large outlay. But we must remember that this is the cost for more than four years work by two men who would have been seen as skilled technicians and project managers, and amounts to around $93,000 a year in 2024 for each man.
From the point of view of Mason and Dixon, perhaps the best value to use is real wage or real income, which measures the purchasing power of an income by its relative ability to buy good and services. When they returned to England, they received around £2,583, or £483,500.00 in 2024 real income. Mason’s share would have been half that, or $303,370 in 2024 dollars, a significant profit if there were no bills to settle back home.
In England, from 1769 to 1785, Mason’s earnings from his work for the Board of Longitude and Greenwich Observatory averaged £130, a sum that was worth around $30,500 a year in 1769, but was worth less on average, $28,383 a year, from 1769 to 1785, in terms of purchasing power in 2024. (The equivalent purchasing power drops after 1769.) Assuming that there were no significant ups and downs in this income, Mason would have earned an average of $28,980 a year from 1776 to 1780 (in 2024 dollars) and $27,173 a year from 1781 to 1785. He also received an additional £950 (for his work on nautical tables and two other projects), but he seems never to have had a significant amount of money despite this additional income and what he received in 1769. In 1786, looking for work in the United States, he immigrated with his family, but fell ill, and died soon after he arrived. (Edwin Danson, Drawing the Line, rev. ed., 2017, p. 210–212)
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Another alternative way of thinking about Mason and Dixon’s wages
Another way of calculating what the surveyors earned and the survey cost might be to update their wages and the known costs as best we can using current surveyor and astronomer salaries and the like, attempting to account for how much the survey would cost by trying to figure out how one would staff and supply a similar survey today.
Currently (2023 to 2025) surveyors get $100,349 on average in Pennsylvania, with a high of $151,590 according to Indeed.[23] ZipRecruiter[24] more or less agrees with that mean salary depending on the state, while the Bureau of Labor Statistics[25] has a lower average, but with higher mean salaries that are around Zip Recruiter’s Pennsylvania average in California. The median annual wage for astronomers was $132,170 in May 2024 according to the Bureau of Labor Statistics[26] and Indeed relies on the BLS information.[27] but according to Zip Recuiter the best you can do is a little less than $55,000 nationally.[28]
One straightforward conversion (mixing sources and not averaging), for 4 years 10 weeks (4.19 years) on the job would be $553,792 for Mason, as an astronomer (using the BLS mean), and $420,462 for Dixon, as a surveyor (using Indeed’s mean), or $974,254 for their work, vs. $644,000–$697,000 (a number which also includes lower wages while traveling and the cost of passage).
Except of course they were paid the same amount. And we know that they were considered relatively highly compensated. How do we factor that in? Is the new result an accurate reflection of the relative purchasing power of their wages? How do we factor in the compensation they receive for their passage to and from America, including being paid a lesser amount while traveling?
Bechtol, as an acknowledged sideline, compared an CPI-inflated value of their passage to the cost of sailing on the QE2 (without taking into account, it appears, the credit they noted on their statement of account). But today you would fly, perhaps in a main cabin seat with extra legroom. And there would be very few days of compensation at a reduced rate while traveling, as a result, assuming a present-day astronomer and surveyor would accept reduced pay for their travel days.
Having solved those issues, how do we do something similar for the various invoices in the Pennsylvania receipts? (Especially if you are not going into Philadelphia to do the research.) As an alternative, you could look at the published records of what the survey crews were compensated, which are extant for the two years of the survey.[29] But what is the equivalent job of an axeman? Someone who works in the logging industry, we’ll assume. But when our modern-day axemen are wielding chainsaws, you don’t need to hire as many. How do you update the cost of all the axemen into terms that are valid today?
And how do you value the zenith sector? (Their zenith sector is either so outdated as to be worthless, or an invaluable antique.) Do you replace it with a GPS receiver in an attempt to determine “real” equivalent costs? If you do that, do you need more than the equivalent of two chainsaw-wielding axemen? And why are you hiring an astronomer? If you ignore advances in technology that make the axemen and the zenith sector obsolete, you can update those costs using the CPI or the like (which is what I more or less did, though the cost of the zenith sector is not in my calculations above), but then you have to decide to do a range when converting those costs, or settle on a particular conversion value, or use an average of the available values. And the figure you end up with is not really equivalent to the suggested revised cost for the surveyors above, so adding the wages of the surveyors and the costs of the survey together is misleading.
This method is flawed because the more accurately you attempt to translate the undertaking into today’s jobs, equipment, and the like, the more likely the result is to underestimate the financial burden borne by the proprietors.
| [1] | “Mason and Dixon Line” entry. https://www.britannica.com/place/Mason-and-Dixon-Line ↩ |
| [2] | This figure corresponds to the sum of the lengths of the West and East lines, and is incorrect. The lines Mason and Dixon marked with monuments and mounds total 316.9 miles (510 km). This includes the portion of the West Line from the Northeast Corner of Maryland and the Tangent, Arc, and North lines. They also surveyed the unmarked portion of the West Line, the East Line, and 14.8 miles from Harlan’s farm to the Post mark’d West, which total a little over 29 miles (46.7 km). ↩ |
| [3] | “Mason-Dixon Line” entry. https://en.wikipedia.org/wiki/Mason%E2%80%93Dixon_line ↩ |
| [4] | William F. Swindler, “Mason & Dixon: Their Line And Its Legend,” American Heritage, February 1964, Vol. 15, No. 2. https://www.americanheritage.com/mason-dixon-their-line-and-its-legend ↩ |
| [5] | https://web.archive.org/web/20081205010941/http://americanheritage.com/articles/magazine/ah/1964/2/1964_2_22.shtml ↩ |
| [6] | https://www.mdlpp.org/_files/ugd/6f029b_2793e4832455490b9ecd811205e9f983.pdf ↩ |
| [7] | No records for June 20 or July 14, 1763 are in the Resurvey’s chronology of manuscripts and publications relating to the Mason and Dixon Line and other lines. ↩ |
| [8] | The Resurvey references the surveyors’ map at this location in the chronology of manuscripts and publications relating to the Mason and Dixon Line and other lines. ↩ |
| [9] | Pence are abbreviated “d.,” from the Latin coin “denarius.” Shillings and pence may also be shown in a format that uses a slash, such as 9/-, or 9 shillings, no pence. ↩ |
| [10] | https://www.minneapolisfed.org/about-us/monetary-policy/inflation-calculator ↩ |
| [11] | https://www.bls.gov/data/inflation_calculator.htm ↩ |
| [12] | https://www.bankofengland.co.uk/monetary-policy/inflation/inflation-calculator ↩ |
| [13] | https://www.mtfxgroup.com/tools/historical-currency-exchange-rates/gbp-to-usd-rate/#exchange-chart 14 https://eh.net/encyclopedia/money-in-the-american-colonies/ ↩ |
| [14] | https://eh.net/encyclopedia/money-in-the-american-colonies/ ↩ |
| [15] | John J. McCusker, John J., How Much is That in Real Money? Worcester, Massachusetts: American Antiquarian Society, 1992. ↩ |
| [16] | https://www.continentalline.org/CL/article-960203/ ↩ |
| [17] | The excepts from the Resurvey in Appendix A below contain several additional, partial statements of costs, such as the money spend on the commissioners. Most of these statements are from 1768 or earlier, and are most likely in the receipts in Pennsylvania pounds. One, however, for Joseph Shippen’s accounts, is from Dec. 24., 1770, and runs from 1763 to 1770, which suggests it may record additional expenses not found among the 1768 receipts. ↩ |
| [18] | https://www.mdlpp.org/_files/ugd/6f029b_2d2b28d346ef41979f5340b6d6af9731.pdf ↩ |
| [19] | Fort Frederick is in Big Pool, MD, about 10 miles SE of Hancock, the town at western Maryland’s narrowest point. ↩ |
| [20] | When the total cost is divided by the days, the result is £1 1s. per day with a remainder of £20. ↩ |
| [21] | It would have been nice to have a total here, so that it could be compared to the total in Pennsylvania pounds above from 1768. ↩ |
| [22] | https://www.measuringworth.com/defining_measures_of_worth.php ↩ |
| [23] | https://www.indeed.com/career/land-surveyor/salaries/PA ↩ |
| [24] | https://www.ziprecruiter.com/Salaries/Licensed-Land-Surveyor-Salary ↩ |
| [25] | https://www.bls.gov/oes/2023/may/oes171022.htm ↩ |
| [26] | https://www.bls.gov/ooh/life-physical-and-social-science/physicists-and-astronomers.htm ↩ |
| [27] | https://www.indeed.com/career-advice/pay-salary/how-much-do-astronomers-make ↩ |
| [28] | https://www.ziprecruiter.com/Salaries/Astronomer-Salary ↩ |
| [29] | See Alvah John Washington Headlee, “The Accompt of the Hands Settling the line between Pennsylvania and Maryland; Summary of the ledgers for the survey during years 1765 & 1767,” 1976, https://www.mdlpp.org/_files/ugd/6f029b_2ae78d4eb9b34ee6b589724c0f0741ab.pdf ↩ |