Irvine () is a city in Orange County, California, United States. It is a planned city, mostly made by the Irvine Company since the 1960s. The city was formally incorporated on December 28, 1971. The 69.7 square mile (180.5 km) city has a population of about 212,793 (as of January 1, 2009). It has united in the past a green belt or greenbelt is a policy and land use designation used in land use planning to retain areas of largely undeveloped area to the north, and has also united the former "El Toro Marine Corps Air Station", most of which is planned to be converted into the "Orange County Great Park".