Thornton Gap was named for Francis Thornton (1711–April 14, 1749), owner of the land to the east and the "F.T. Valley". In 1740, he built a mansion in the Piedmont region near Nethers in Rappahannock County.[1]
Historian J. Houston Harrison indicates in 1737 the Harrison family migrated through the Gap from Alexandria before their settlement in the valley and founding of Harrisonburg.[2]
The privately owned Thornton's Gap Turnpike Company was formed to build a road over the mountains at Thornton's Gap. The toll road opened in 1806.
Thornton Gap was one of the passages through the Blue Ridge Mountains between the Shenandoah Valley and the Piedmont region of Virginia used by Confederate General Stonewall Jackson to move his famous "foot cavalry" troops during the American Civil War.