U.S. Route 399, is a U.S. Highway that starting from Ventura, California end to Bakersfield, California. It was established in 1934 & deleted in 1964, as it was having only 137 miles long, less than the minimum 300 miles that AASHTO set as the threshold for U.S. Highways. It has been put back with a part of State Route 33, all of State Route 119, & a segment of State Route 99. It having the state of California.