The line was extended in 1779 and 1780 to the point at which it would first cross the Cumberland River. From there, the state of Virginia hired Thomas Walker to survey the line to the Mississippi River. Walker did not do a perfect job due to dense virgin forest, mountainous terrain, and rough riverbeds. In 1821 the state of Tennessee did a survey of the line to determine its true border with Kentucky, but this was not resolved since Kentucky was not participating. A joint survey by the two states was conducted in 1859, commanded by Austin P. Cox and Benjamin Pebbles. They started a 320-mile survey from the New Madrid Bend of the Mississippi River to the Cumberland Gap, placing a 3-foot-high stone slab every five miles.

It was a brainchild of King Charles II of England, and was intended to stretch from the Atlantic to the Pacific Ocean. By 1819 it was surveyed as far west as the Mississippi River near New Madrid, Missouri.

The line would later be used for approximating a de facto boundary north of which slavery could not be practiced, as established in the Missouri Compromise of 1820. A marker at the Cumberland Gap National Historical Park denotes where the boundaries of Kentucky, Tennessee, and Virginia intersect. Under the Royal Proclamation of 1763 it also marks how far west a British American colonist was allowed to reside. Its exact location is N 36'36.045, W 83'40.518.