There are two Busch Gardens theme parks currently operating in the United States (not four—the St. Louis parks closed in 1979 and 1984):
Former Parks: Busch Gardens Houston (1971–1973), Busch Gardens Van Nuys (LA, 1964–1979), Busch Gardens St. Louis (1971–1979), Grant's Farm (St. Louis, animal preserve, remains open).
Both current parks are owned by United Parks & Resorts (formerly SeaWorld Parks & Entertainment). They combine world-class thrill rides with accredited zoological facilities.