Los Angeles County, officially the County of Los Angeles, is the most populous county in the United States, with more than ten million inhabitants as of 2018. It is the largest non–state-level government entity in the United States. Its population is greater than that of 41 individual U.S. states. It has the third-largest metropolitan economy in the world, with a Nominal GDP of more than $700 billion. It has 88 incorporated cities and many unincorporated areas and, at 4,083 square miles (10,570 km2), it is larger than the combined areas of Delaware and Rhode Island. The county is home to more than one-quarter of California residents and is one of the most ethnically diverse counties in the United States. Its county seat, Los Angeles, is also California's most populous city and the second most populous city in the United States, with about four million residents.