State Route 33 (
SR 33) is a north–south
state highway in the
U.S. state of
California. It runs north from
Ventura through the
Transverse Ranges and the western side of the
San Joaquin Valley to a point east of
Tracy. SR 33 replaced part of
U.S. Route 399 in 1964 during the "great renumbering" of routes. In the unincorporated sections of
Kern County it is known as the
West Side Highway. In addition, the California Legislature designated the entire Kern County portion as the
Petroleum Highway in 2004. The southernmost portion in Ventura is a freeway known as the
Ojai Freeway, while it is known as the
Maricopa Highway from
Ojai to
Maricopa.