The road was first commissioned in 1913 as the multi-national Paciic Highway Auto Trail, which ran from Vancouver, BC to San Diego. It was among the first paved roads in the Pacific Northwest. In 1926, the American Association of State Highway and Transportation Officials (AASHTO) set up a new proposed system of national numbered highways. In 1926, many of these proposed highways were approved by Congress and replaced the auto trail system. The Pacific Highway below halfway between Red Bluffs and San Francisco in California became U.S. Routes 101 and 40. The rest became U.S. Route 99, which split from the Pacific Highway at the intersection of new U.S. Route 40 and continued south to El Centro (it was later extended to Calexico and then truncated to Los Angeles even later).