KGST, known for much of its history as "La Mexicana," started out as a mixed-format "international" station in 1949, with programs hosted by brokers who paid for airtime. It featured programming in languages including Armenian, Portuguese, Serbian, Italian, Japanese and Spanish-language. It was the first radio station in the San Joaquin Valley with Spanish-language programming, and one of the earliest stations in California with full-time programming in Spanish.
Juan Mercado, who got his start as the Spanish-language programming director at a Visalia station, was one of the most popular deejays at the station, becoming so successful that he was able to buy the station in 1959. Mercado died just two years later and the station was bought by a couple of men who were at the time running KLOK out of San Jose.
In 1988, KGST was bought by Lotus Corporation, which owned several stations in Arizona, California and Nevada.