Mason and Dixon's Line
Aiton's Encyclopedia (1910)
a line forming the northern and the eastern boundary of Maryland. It takes its name from Charles Mason and Jeremiah Dixon, two English engineers. Disputes having arisen between colonists, these surveyors were sent over by the Baltimores, proprietors of Maryland, and by the heirs of William Penn, proprietors of Pennsylvania, to fix the boundary. They did their work between the years of 1764 and 1767, and did it with so much accuracy that a re-survey in 1849 discovered no errors of importance. In 1901-3, to settle local disputes, a joint appropriation of $5,000 was expended by the states of Pennsylvania and Maryland in marking the line from Delaware westward. It is a straight east and west line. Its eastern continuation would pass just fifteen miles south of Philadelphia. Midway it coincides with the parallel of 39 deg. 43' 26.3" north latitude. Mason and Dixon brought milestones with them from England. These were of limestone, four and one-half feet in length and a foot square. One side bore M for Maryland, the other P for Pennsylvania. On every fifth stone were chiseled the arms of the proprietors. The stones weighed 500 pounds each. The surveyors of 1901 found that many of these stones had disappeared or had been put to strange uses, such as doorsteps. Some were rescued from foundations. Two had been used in constructing a church. One in Clear Springs, Maryland, was serving as a curb stone; others were found built into bake ovens, etc. It was known that a sufficient number of stones was imported to mark the entire line. It is conjectured that, owing to their great weight and the lack of roads in some localities, loads of the stone were left here and there and never set up. Toward the western end of the line, in particular, mounds of earth and wooden posts were found doing duty in their stead. By a diligent search the surveyors succeeded in recovering all but seventy-five of the missing stones. Broken ones were repaired with iron clamps. To prevent their removal, they were set up in concrete foundations. The missing milestones were replaced by new marble stones. In United States history, Mason and Dixon's Line is known as the dividing line between slavery and freedom. It should not be confounded with the compromise line of 36 deg. 30' north latitude. See Dixie
What Has Changed in the Last Century
The boundary Aiton's described in 1910 is still the legal line between Maryland and Pennsylvania (and Delaware), and the 1901-03 remonumentation it praised remains largely the framework surveyors work from, with later joint state re-surveys confirming Mason and Dixon's work to within a few feet. Two corrections of emphasis: the pair were not "engineers" but astronomers, sent to America in the first place for observations connected to the transit of Venus, and their line stopped short of the full western distance in 1767 when their Iroquois escort refused to go further, the remainder being run only after the Revolution. The surviving limestone markers, which the 1901 surveyors found doing duty as doorsteps, curbstones and bake-oven walls, are now protected and periodically inventoried as historic monuments rather than working boundary stones. The cross-reference to "Dixie" reflects a folk etymology from Dixon's name that modern scholars regard as unproven; and where 1910 called the line the divide "between slavery and freedom", it now functions purely as cultural shorthand for the North-South boundary, revived for general readers by Thomas Pynchon's 1997 novel Mason & Dixon.
Written for this edition, 2026.