U.S. Route 66 or U.S. Highway 66 (US 66 or Route 66), also known as the Will Rogers Highway, the Main Street of America or the Mother Road, was one of the original highways in the U.S. Highway System. The numerical designation 66 was assigned to the Chicago-to-Los Angeles route on April 30, 1926 in Springfield, Missouri. A placard in Park Central Square was dedicated to the city by the Route 66 Association of Missouri, and traces of the "Mother Road" are still visible in downtown Springfield along Kearney Street, Glenstone Avenue, College, and St. Louis streets and on Route 266 to Halltown, Missouri.

It runs through eight states starting from Chicago, Illinois, through Missouri, Kansas, Oklahoma, Texas, New Mexico, and Arizona before ending in Santa Monica in Los Angeles County, California, covering a total of 2,448 miles (3,940 km). It was recognized in popular culture by both the hit song "(Get Your Kicks on) Route 66" and the Route 66 television series, which aired on CBS from 1960 to 1964. In John Steinbeck's classic American novel, The Grapes of Wrath (1939), the road "Highway 66" symbolized escape and loss.

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