San Luis Obispo, or SLO /sloʊ/ for short, is a city in the U.S. state of California, located roughly midway between Los Angeles and San Francisco on the Central Coast. The population was 45,119 at the 2010 census. The population of San Luis Obispo County was 269,637 in 2010.Founded in 1772 by Spanish Franciscan Junípero Serra, San Luis Obispo is one of California's oldest communities. Serra's original mission was named for the 13th-century saint and bishop Louis of Toulouse. The city, locally referred to as San Luis, SLO, or SLO Town is the county seat of San Luis Obispo County and is adjacent to California Polytechnic State University.