San Francisco is the second most densely populated major city in the country, with about 18,600 people per square mile. Shared walls, old wood framing and food businesses on nearly every block give pests plenty of ways to move between buildings.
San Francisco is a consolidated city and county, and the 2020 census counted 873,965 residents. About 47 square miles of it is land, which makes it the second densest large city in the United States. The terrain climbs from sea level to 934 feet at Mount Davidson, and the city wraps around the San Francisco Bay, with Golden Gate Park and the Presidio providing large stretches of green space.
A sea of Victorian houses spread across the peninsula after the 1870s, and many of those wooden buildings are still divided into flats today. Old wood, shared walls and the constant flow of food and packages through neighborhoods such as the Mission District, Nob Hill and Chinatown suit pests that live close to people. Where one building has a problem, the next one usually hears about it soon.
