On October 18, 1767, the Mason-Dixon survey was completed. The resulting Mason-Dixon line is a boundary that set parts of the borders between Pennsylvania, Maryland, Delaware, and Virginia (today, West Virginia). The Mason-Dixon line is often recognized as the division between the U.S. North and South.

This was not the original intent for the line. As a result of border disputes between the colonies of Maryland and Pennsylvania, Charles Mason and Jeremiah Dixon were asked to determine an official boundary. Mason was an astronomer with the Royal Observatory, Greenwich, in London, England. He used observations of stars to determine longitude. Dixon was a surveyor, also from England. Between the two, they slowly and accurately determined a boundary and marked it with stones. The Mason-Dixon line follows a latitude of 39 degrees and 43 minutes north of the Equator.

The Mason-Dixon line runs for 375 kilometers (233 miles), and the survey took five years to complete.

accurate
Adjective

exact.

astronomer
Noun

person who studies space and the universe beyond Earth's atmosphere.

border
Verb

to exist on the edge of a boundary.

Noun

line separating geographical areas.

determine
Verb

to decide.

dispute
Noun

debate or argument.

Noun

distance north or south of the Equator, measured in degrees.

Noun

distance east or west of the prime meridian, measured in degrees.

north
Noun

direction to the left of a person facing the rising sun and the leading direction on a compass.

recognize
Verb

to identify or acknowledge.

South
Noun

loosely defined geographic region largely composed of states that supported or were sympathetic to the Confederate States of America (Confederacy) during the U.S. Civil War.

surveyor
Noun

person who analyzes the specific boundaries and features of a piece of land using mathematical concepts such as geometry.