Chowchilla is a city in Madera County, California, United States. The city's population was 19,039 at the 2020 census. Chowchilla is located 16 …Chowchilla is a city in Madera County, California, United States. The city's population was 19,039 at the 2020 census. Chowchilla is located 16 miles northwest of Madera, at an elevation of 240 feet. The city is the location of two prisons: Central California Women's Facility and Valley State Prison.