In American history the key word is expansion. The original 13 colonies were settled on the Eastern Seaboard, limited, for practical purposes, by the Appalachian Mountains. Well before the Revolution, solitary pioneers, of whom Daniel Boone was the most famous, did indeed carry out important explorations across the Appalachian Mountains, but penetration westward remained halting and irregular until after the colonies became welded into a new nation.
As with virtually all folk migrations, population pressures induced hardy and ambitious settlers to seek new land, new opportunities. Physical difficulties of terrain, and the hostility of Indians whose lands were being ruthlessly seized, served as counterbalancing forces, but population pressures were not to be denied.
The new government had wisely established what might be called a reservoir of land open to settlers. In the latter 18th century the best route to the so-called Northwest Territory lay along the Ohio Valley. Roads were
King LS. Who Was Daniel Drake?. JAMA. 1985;254(15):2111-2112. doi:10.1001/jama.1985.03360150087030