Sierra College, a California community college, has its main campus located in Rocklin, California. Rocklin is located in the foothills of the Sierra Nevada Mountains, approximately twenty minutes from the state capital of Sacramento and 105 miles (169 km) east of San Francisco. The campus lies within the watershed of Secret Ravine, a site of mining operations during the California Gold Rush. In addition to the 300-acre (1.2 km) Rocklin campus, the District has a 115-acre (0.47 km) campus in Grass Valley which is in neighboring Nevada County, a campus center in Truckee, and a campus center in Roseville. The Sierra Community College District, a district that covers over 3,200 square miles (8,300 km), serves Placer, Nevada and parts of El Dorado and Sacramento counties. Sierra College's origin is unclear. Some say the establishment of the Sierra Normal College and Business Institute in 1882, a small, private college at the location of today’s Placer High School in Auburn, California, was later formed into Sierra College. It is commonly thought, however, that Sierra College is the outgrowth of the Placer Union High School District.