Alta is a small unincorporated community in Placer County, California, United States, about 30 miles (48 km) northeast of Auburn. The village is located off Interstate 80 and along the historical First Transcontinental Railroad. The ZIP code is 95701 and the area code 530. One of the few buildings other than private residences is the Alta-Dutch Flat Grammar School serving kindergarten through eighth grade students. The high school that serves Alta is Colfax high School, is 11 miles east in the incorporated town of Colfax. A historical California place once named Alta was located in San Diego County near the present-day La Mesa-El Cajon boundary. This historical place was along the San Diego and Arizona Eastern Railway, now the San Diego Trolley Orange Line, at its Murray Drive undercrossing in La Mesa.