Just to add some where and when to the post, there were a number of automobile assembly plants in Southern California dating back to 1916. Below is a list, which may be incomplete. This list does not include several truck assembly plants that were located in Southern California as well.

Bob Chaparro

Hemet, CA

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Southern California Automobile Assembly Plants

Chrysler

Commerce, 1929-1971

Ford

Los Angeles, 1916-1930 (Santa Fe?)

Pico Rivera, 1957-1980 (Santa Fe)

Long Beach, 1930–1959

Commerce (Lincoln-Mercury)

General Motors

South Gate, 1936-1982

Van Nuys, 1947-1992 (Southern Pacific)

Kaiser Frazer

Long Beach, 1947-1955?

Nash Motors

El Segundo, 1948-1955

Studebaker

Vernon, 1936-1956 (Los Angeles Junction Railway)

Toyota (Truck Beds)

Long Beach, 1972-2004

Willys-Overland

Maywood 1928-1954