The National Road (also known as the Cumberland Road) was the first major improved highway in the United States built by the federal government. Built between 1811 and 1837, the 620-mile (1,000 km) road connected the Potomac and Ohio Rivers and was a main transport path to the West for thousands of settlers. When improved in the 1830s, it became the second U.S. road surfaced with the macadam process pioneered by Scotsman John Loudon McAdam.Construction began heading west in 1811 at Cumberland, Maryland, on the Potomac River. After the Financial Panic of 1837 and the resulting economic depression, congressional funding ran dry and construction was stopped at Vandalia, Illinois, the then capital of Illinois, 63 miles (101 km) northeast of St. Louis across the Mississippi River.

The road has also been referred to as the Cumberland Turnpike, the Cumberland–Brownsville Turnpike (or Road or Pike), the Cumberland Pike, the National Pike, and the National Turnpike.In the 20th century with the advent of the automobile, the National Road was connected with other historic routes to California under the title, National Old Trails Road. Today, much of the alignment is followed by U.S. Route 40 (US 40), with various portions bearing the Alternate U.S. Route 40 (Alt. US 40) designation, or various state-road numbers (such as Maryland Route 144 for several sections between Baltimore and Cumberland).

In 1976, the American Society of Civil Engineers designated the National Road as a National Historic Civil Engineering Landmark. In 2002, the entire road, including extensions east to Baltimore and west to St. Louis, was designated the Historic National Road, an All-American Road.