Near Cumberland Gap, Meriwether Lewis made a discovery with major importance for Kentucky and Tennessee when he used his sextant to determine the true latitude in an effort to settle a long dispute over the Tennessee-Kentucky state line. For 27 years, no one agreed on where the boundary actually lay in these mountains, even though both states held that it should be at latitude 36 degrees 30 minutes north. In 1779, the Virginia legislature had asked Dr. Thomas Walker to lead a party surveying Virginia's southern boundary, while North Carolina appointed Colonel Richard Henderson to run the same line west. On November 23, 1806, after Lewis and William Clark passed separately through Cumberland Gap on their way home and later reported to President Jefferson in Washington during the winter of 1806–07, Lewis undertook to settle the latitude of Walker's Line near the habitation of a Mr. Walling, about two miles from Cumberland Gap. He found that the old Walker survey had placed the line almost 10 miles too far north, writing that Walker's Line was nine miles and 1,077 yards north of its proper position. Kentucky and Tennessee eventually reached a compromise boundary some 14 years later.