 This was the first film of a planned trilogy about corruption in the  development of Los Angeles. "Chinatown" was set in the 1930s and was  about the water department. The second film called "The Two Jakes",  which was completed and released. It was set in the 1940s, and was  about the gas company. The third film of the trilogy was about the  building of the massive freeway system and was to be called  "Cloverleaf", named after the famous interchange in downtown, but it  was never filmed.