Anza-Borrego Desert State Park is a vast protected landscape in Southern California’s Colorado Desert, centered on Borrego Valley and spanning parts of San Diego, Imperial, and Riverside counties. Created in 1932 and named for Juan Bautista de Anza and the Spanish word borrego, it is California’s largest state park. Its terrain ranges from badlands and broad desert basins to mountains, oases, springs, and valleys, supporting about 600 native plant species and diverse wildlife, including endangered peninsula bighorn sheep. The park is also scientifically important for fossil-bearing sediments that record a long transition from sea to desert, and today it is a major destination for outdoor recreation and dark-sky viewing.