South Gate Assembly was a General Motors automobile plant located in the Los Angeles suburb of South Gate, California. It opened in 1936 to build B-O-P (Buick-Olds-Pontiac) cars for sale on the west coast. It was the first GM plant to build multiple car lines, resulting from a Depression-spawned move to cut production costs by sharing components and manufacturing. South Gate was the second of several B-O-P "branch" assembly plants (the first being the Buick-operated Linden plant), part of GM's strategy to have production facilities in major metropolitan cities. The location was under the management of GM's newly created Buick-Oldsmobile-Pontiac Assembly Division created in 1945.
It was located at 2720 Tweedy Boulevard, South Gate, California.
These "branch" plants would build cars for distribution to a specific region. By 1949 it was producing full size cars from the Chevrolet, Pontiac, Oldsmobile, Buick and Cadillac brands. During the mid-1950s it was General Motors' highest-output plant. Vehicles included the Oldsmobile 98, Pontiac Streamliner, Buick Special, and the Cadillac Series 61.
It added production of the Pontiac Tempest, Oldsmobile F-85, and Buick Special alongside the fullsize cars for 1961. When the compacts became intermediates for 1964 their production ceased at South Gate, and Chevrolet Impala fullsize production was added, after the Buick-Oldsmobile-Pontiac Assembly Division was renamed GM Assembly Division (GMAD) in 1965.
The plant was converted from full-size car production to the subcompact Chevrolet Vega for 1975. This arrangement was short-lived, and GM returned the factory to building full-size Chevrolet, Olds, and Buick B-body vehicles for 1977. The Olds and Buick were dropped and the Cadillac DeVille added for 1979. However, due to decreasing sales of the Chevrolet B-body cars, it was idled in March 1980. It was then retooled once again for subcompacts, building the 1982 Chevrolet Cavalier and Cadillac Cimarron. Slow sales and efforts to reduce air quality issues resulted in the closure of the plant, with production ending on March 23, 1982.
The plant site was later environmentally remediated and used as the location for new schools, including South East High School (opened 2005), which were built by the Los Angeles Unified School District to relieve severe congestion in the existing schools of South Gate.
Buick-Oldsmobile-Pontiac Assembly Division (1945-1965)
Plants operating under Chevrolet Assembly management prior to General Motors Assembly Division management (most established pre-1945) were located at St. Louis, Missouri; Janesville, Wisconsin; Buffalo, New York; Norwood, Ohio; Flint (#2), Michigan; Oakland, California; Tarrytown, New York; Lakewood, Georgia; Leeds, Missouri; Baltimore, Maryland; Los Angeles (Van Nuys), California; Ypsilanti (Willow Run), Michigan; and Lordstown, Ohio. Framingham, Massachusetts is unusual in that it changed from B-O-P to Chevy management prior to becoming GMAD.
The terminology is confusing because most plants assembled more than just Chevrolet or B-O-P, and refers to the management structure only. The five brands originated vehicles from their respective "home" plants, where vehicles were assembled locally for their respective regions. Vehicles were also produced in "knock-down" kits and sent to the branch assembly locations. The "home" branches were Flint, Michigan for both Buick and Chevrolet; Oldsmobile at Lansing, Michigan; Pontiac at Pontiac, Michigan; and Cadillac at Detroit, Michigan.