What made Cumerland Road important during the 19th century?

The National Road (also known as the Cumberland Road) [1] 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 rebuilt in the 1830s, it became the second U. S. road surfaced with the macadam process pioneered by Scotsman John Loudon McAdam.[2]