The city forms the central populated core of the Conejo Valley. Thousand Oaks was incorporated in 1964, but has since expanded to the west and east. Two-thirds of neighboring Westlake Village and most of Newbury Park were annexed by the city during the late 1960s and 1970s. The Los Angeles County–Ventura County line crosses at the city's eastern border with Westlake Village. The population was estimated to be 129,339 in 2015, rising from 126,683 at the 2010 census. Thousand Oaks is 55 square miles, which, for comparison, is 20 percent larger than San Francisco.