American Heritage Magazine
February 1964 Volume 15, Issue 2
Mason & Dixon: their Line and its Legend - By A. HUGHLETT MASON and WILLIAM F. SWINDLER
Lines on maps may be drawn by engineers, but they are interpreted by political events.
Seldom has history recorded an amicable and abiding acceptance of such demarcations
when they involve restless dynastic movements, whether the example be Pope Alexander
VI’s division of the New World in 1493 between Spain and Portugal, or the twentieth
century’s unhappy establishment of the border between East and West Berlin after World
War II. The surveyor’s work becomes a symbol, and his name may become a catch
phrase for a congeries of political and social issues of which he never dreamed.
The prime illustration of such an event in the United States is the line laid out for a total
of about 332 miles by two English astronomer-surveyors between 1763 and 1767, to
settle a dispute between the Perms and the Baltimores. For more than eighty years these
powerful proprietaries had contended over the precise location of their common border.
When they finally settled upon these two scientists to direct an impersonal,
mathematically dependable survey, they set the stage for an engineering feat of
impressive dimensions for that time.
But Charles Mason and Jeremiah Dixon were destined to be remembered for their
substantial engineering and scientific accomplishments only in the annals of specialists.
Mason, among other things, later completed a catalogue of 387 stars, which, when
incorporated into a nautical almanac published in 1787, became the standard authority on
the subject for a number of years. Dixon, a county surveyor and amateur astronomer, was
considered sufficiently adept in his field to be elected to the Royal Society. He took part
in several overseas scientific expeditions for the Society.”
For considerably more than a century, however, what the average American has
understood by the Mason-Dixon survey has been a figurative division between two
frames of reference in national life. Just as the South—and, for that matter, the North—
tended to become a state of mind, so the Mason-Dixon Line has come to be viewed only
incidentally as a real border and more as a line of transition between these two states of
mind. In the national psychology it is thought of as a jagged extension of the border
between Pennsylvania and Maryland to some vaguely defined point on the Missouri-
Kansas border.
Just when this popular concept first took shape is not easy to say. Obviously, as sectional
consciousness in the matter of slavery increased in the first half of the nineteenth century,
the fact that Maryland, the most northerly slave state, was divided from Pennsylvania’s
free soil by the Mason-Dixon survey impressed itself upon the public mind. The Ohio
River, as the border between the southern state of Kentucky and the Northwest Territory,
where slavery was prohibited, was a natural landmark extending the symbolism of the
Mason-Dixon Line, the western terminus of which lay close to that great waterway to the
West. Finally, the Missouri Compromise, fixing the northern limit of slave territory at
latitude 36 degrees 30 minutes north, westward from the Ohio’s juncture with the
Mississippi, completed the popular image.
The issues which thus developed in the nineteenth century around Mason and Dixon’s
survey, and made their names a household phrase, have largely obscured the significant
political and scientific results of the original project. That project—a border settlement of
the eighteenth century—in turn traced its beginnings to issues which arose in the
seventeenth century, and even earlier. The problem really started with England’s belated
decision to launch her own colonizing efforts in the New World, where Spain and
Portugal had long preceded her and where she now found the Netherlands, Sweden, and
France in close competition.....................
