Which organization first signed U.S. Route 66 in California in 1928?

The Automobile Club of Southern California first signed U.S. Route 66 in California in 1928.

Route 66 had been assigned nationally in November 1926, but physical signs were installed separately from the designation process. In California, the Automobile Club of Southern California helped identify and mark the road for motorists.

The California section followed older corridors, including the National Old Trails Road, before reaching San Bernardino, Pasadena, Los Angeles, and the Pacific coast. The route’s western end was later extended from Los Angeles to Santa Monica in 1935.

This signing work helped turn a paper route into a practical transcontinental highway. Automobile clubs played an important role in early American motoring by publishing maps, marking roads, and assisting travelers before modern highway departments and interstate-style signage became standard.