Fresno is a city in California, United States, and the county seat of Fresno County. It covers about 112 square miles in the center of the San Joaquin Valley, the southern portion of the California's Central Valley.Named for the abundant ash trees lining the San Joaquin River, Fresno was founded in 1872 as a railway station of the Central Pacific Railroad before it was incorporated in 1885. The city has since become an economic hub of Fresno County and the San Joaquin Valley, with much of the surrounding areas in the Metropolitan Fresno region predominantly tied to large-scale agricultural production.The population of Fresno grew from a 1960 census population of 134,000 to a 2000 census population of 428,000. With a census-estimated 2016 population of 520,159, Fresno is the fifth-most populous city in California, the most populous city in the Central Valley, the most populous inland city in California, and the 34th-most populous city in the nation.