Cerritos (formerly known as Dairy Valley) is a city in Los Angeles County, California, United States, and is one of several cities that constitute the Gateway Cities of southeast Los Angeles County. It was incorporated on April 24, 1956. The current OMB metropolitan designation for Cerritos is "Orange County-Long Beach-Santa Ana, CA. " According to the California Department of Finance, the population was 55,074 as of 2005.