Irvine is a suburban incorporated city in Orange County, California, United States. It is a planned city, mainly developed by the Irvine Company since the 1960s. Formally incorporated on December 28, 1971, the 66 square miles (170 Square kilometre) city has a population of 212,375 as of the 2010 census. However, the California Department of Finance estimates its 2011 population to be 219,156. It has annexed in the past an undeveloped area to the north, and has also annexed the former El Toro Marine Corps Air Station, most of which is planned to be converted into the Orange County Great Park.