Thousand Oaks is the second-largest city in Ventura County, California, United States. It is in the northwestern part of the Greater Los Angeles Area, approximately 35 miles from Downtown Los Angeles and is less than 15 mi from the Los Angeles city neighborhood of Woodland Hills. It was named after the many oak trees that grow in the area, and the city seal is adorned with an oak.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, up from 126,683 at the 2010 census. Thousand Oaks is 55 square miles, which, for comparison, is 20 percent larger than San Francisco.