In 1810 Rockcastle County was created primarily from Lincoln and Madison counties, and the area's justices of the peace were instructed to meet at Stephen Langford's dwelling-house on the first Monday in April to organize the county government. The earliest reference to the town as Mount Vernon dates to August 1811. By 1796 other people and families had moved into the Langford's Station vicinity, including Long Hunter Valentine Harmon and William Henderson. A document that survived the 1873 courthouse fire shows that the original town was rectangular, 985 feet wide and 2,140 feet long, covering almost 51 acres. Main and Center streets ran lengthwise through the town, while High Street, West, Middle, and East streets ran perpendicular to them, and an alleyway encircled the town to allow for expected future expansion. Portions of this original layout remain visible today, with Main Street still Main Street, Center now U.S. 25, Middle now Church Street, and West now a combination of McFerron and Richmond, while High Street no longer exists and part of East Street has disappeared.