Porterville is a city in the San Joaquin Valley, in Tulare County, California, United States. It is part of the Visalia-Porterville metropolitan statistical area.Since its incorporation in 1902, the city's population has grown as it annexed nearby unincorporated areas. The city's July 2014 population was estimated at 55,466.Porterville serves as a gateway to Sequoia National Forest, Giant Sequoia National Monument and Kings Canyon National Park.