U.S. Route 399

U.S. Route 399
US 399 highlighted in red
Route information
Auxiliary route of US 99
Maintained by Caltrans
Length	124 mi[1] (200 km)
Existed	1934–1964
Major junctions
South end	US 101 in Ventura
North end	US 99 in Bakersfield
Location
Country	United States
State	California
Counties	Ventura, Santa Barbara, San Luis Obispo, Kern
Highway system
United States Numbered Highway System List Special Divided State highways in California Interstate US State Scenic History Pre‑1964 Unconstructed Deleted Freeways
← US 395 → I-405

U.S. Route 399 was a U.S. Highway in the state of California that ran from Ventura to Bakersfield. It was established in 1934 and decommissioned in 1964, as it was only 124 miles (200 km) long, less than the 300-mile (480 km) minimum that the American Association of State Highway and Transportation Officials (AASHTO) set as the threshold for U.S. Highways. It has been replaced with a segment of State Route 33 (SR 33), all of SR 119, and a segment of SR 99.