On what date was U.S. Route 66 officially established as part of the U.S. Highway System?

U.S. Route 66 was officially established on November 11, 1926, when the United States numbered highway system was created.

The new highway linked Chicago with Los Angeles through Illinois, Missouri, Kansas, Oklahoma, Texas, New Mexico, and Arizona. Its original western endpoint was Los Angeles; the route was later extended to Santa Monica in 1936.

Route 66 was one of the original highways in the national numbering plan. A common mix-up is treating 1926 as the date it was fully paved, but construction and paving continued for years afterward. The route was decommissioned in 1985 after newer interstate highways replaced it.