Miami : is a 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 proper in the United States, with a population of 408,568, it is the principal, central, and most populous city of the Miami metropolitan area, and the most populous metropolis in the Southeastern United States. According to the U.S. Census Bureau, Miami's metro area is the seventh most populous and fifth-largest urban area in the United States, with a population of around 5.5 million. Time zone EST (UTC-5) , ZIP code(s) 33010–33299 , Area code(s) 305, 786 , Currency USd. $ .