Miami is a major city located on the Atlantic coast in southeastern Florida and the county seat of Miami-Dade County, the most populous county in Florida and the eighth-most populous county in the United States with a population of 2,500,625. The 42nd largest city in the United States, with a population of 433,136, it is the principal, central, and most populous city of the South {Florida} metropolitan area, the most populous metropolis in the Southeastern United States. According to the US Census Bureau, Miami's metro area is the seventh most populous in the United States, with an estimated population of 5,547,051 in 2009.