Stanislaus is one of the 58 counties in the state of California. It was created in 1854 from part of Tuolumne county. As of the 2010 census the population was 514,453, up from 446,997 in 2000. The county seat and largest city is Modesto.
The county has 1,514.67 square miles (3,923.0 km2) of area, of which 1,493.79 sq mi (3,868.9 km2) is land. It is bordered by Calaveras County on the north, Tuolumne County on the northeast, Mariposa County to the southeast, Merced County to the south, Santa Clara County to the west, and Alameda and San Joaquin counties to the northwest.