Route 66 (also known as U.S. Route 66, The Main Street of America, The Mother Road and the Will Rogers Highway ) was a highway in the U.S. Highway system. One of the original federal routes, US 66 was established on November 11, 1926, though signs did not go up until the following year. It originally ran from Chicago, Illinois, through Missouri, Kansas, Oklahoma, Texas, New Mexico, Arizona, and California, before ending at Los Angeles for a total of .

Route 66 underwent many improvements and realignments over its lifetime that changed its overall length. One of these realignments moved the western endpoint from downtown Los Angeles to Santa Monica. Contrary to common belief, Route 66 never ran to the coast; it terminated onto what was at the time US-101 ALT, at what is today the intersection of Olympic Boulevard and Lincoln Boulevard (a segment of State Route 1). It never went to the intersection of Ocean Boulevard and Santa Monica Boulevard, even though there is a plaque dedicating Route 66 as the Will Rogers Highway there.

Route 66 was a major path of the migrants who went west, especially during the Dust Bowl of the 1930s, and supported the economies of the communities through which the road passed. People doing business along the route became prosperous due to the growing popularity of the highway, and those same people later fought to keep the highway alive even with the growing threat of being bypassed by the new Interstate Highway System.

US 66 was officially decommissioned (that is, officially removed from the United States Highway System) on June 27, 1985 after it was decided the route was no longer relevant and had been replaced by the Interstate Highway System. Portions of the road that passed through Illinois, New Mexico, and Arizona have been designated a National Scenic Byway of the name "Historic Route 66". It has begun to return to maps in this form.

"(Get Your Kicks on) Route 66", often rendered simply as "Route 66", is a popular song and rhythm and blues standard, composed in 1946 by American songwriter Bobby Troup. It was first recorded in the same year by Nat King Cole, and was subsequently covered by many artists including Chuck Berry and The Rolling Stones. The song's lyrics follow the path of the U.S. Route 66 highway, which used to run a large distance across the US, going from Chicago, Illinois to Los Angeles, California. The title was suggested to Troup by his first wife, Cynthia.