The Alameda-Contra Costa Transit District (AC Transit) bus fleet, serving the counties of Alameda and Contra Costa, is the third-largest in California. It was initially formed in 1960 with a mixture of gasoline and diesel-powered buses purchased from its immediate predecessor, the privately-owned Key System. The first new buses were purchased for AC Transit in 1960, shortly after its formation and the GM New Look buses were delivered later that year. The transit agency operated GM buses exclusively until 1974, when the first Flxible New Look buses were ordered. Since then, AC Transit has ordered and operated buses from most of the major North American transit bus manufacturers, including Flyer, Gillig, Motor Coach Industries, Neoplan USA, and North American Bus Industries, as well as Van H