County Seat: Yuma
Founded: 1864
Area: 5,514 square miles
Population: 195,751 (2010)
Other Major City: San Luis
Geographic Highlights: Yuma County includes the Kofa National Wildlife Refuge and part of Cabeza Prieta National Wildlife Refuge. The city of Yuma rose to prominence as an early Colorado River crossing, and the Ocean-to-Ocean Bridge, the first vehicle bridge across the river, is located there.