Orange County is a county in the U.S. state of California bordering the Pacific Ocean. As of the 2010 census, the population was 3,010,232[5] making it the third-most populous county in California, the sixth-most populous in the United States, and more populous than twenty-one U.S. states.[6] Its county seat is Santa Ana.[7] It is the second most densely populated county in the state, second only to San Francisco County.[8] The county's four largest cities, Anaheim, Santa Ana, Irvine, and Huntington Beach each have populations exceeding 200,000.