San Mateo is the most populous city in San Mateo County, California, United States, on the San Francisco Peninsula. It is part of the San Francisco Bay Area metropolitan region, and is located about 20 miles (32 km) south of San Francisco. San Mateo borders Burlingame to the north, Hillsborough to the west, San Francisco Bay and Foster City to the east and Belmont to the south. The population was 105,661 at the 2020 census. Some of the biggest economic drivers for the city include technology, health care and education.