The National Road—formally the Cumberland Road and later celebrated as "Main Street of America"—was the United States' first great federally financed highway and a proving ground for national‑scale internal improvements.
Originating at the head of navigation on the Potomac River in Cumberland, Maryland, the 4-rod (66 ft; 20 m) wide engineered turnpike was authorized on March 29, 1806 when President Thomas Jefferson signed "An Act to regulate the laying out and making a road from Cumberland … to the State of Ohio". Surveyors ran a 131-mile (211 km) alignment over the Allegheny Mountains to Wheeling, Virginia, on the Ohio River by 1818, building a stone‑surfaced, cambered roadway, masonry bridges, culverts, and cast‑iron mileposts that set standards for antebellum turnpikes.