Miami ( or ) 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 ninth-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 399,457, 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.
Miami is a major center and a leader in finance, commerce, culture, media, entertainment, the arts, and international trade. In 2010, Miami ranked seventh in the United States in terms of finance, commerce, culture, entertainment, fashion, education, and other sectors. It ranked thirty-third among global cities.
In 2008, Miami was ranked as "America's Cleanest City" according to Forbes Magazine for its year-round good air quality, vast green spaces, clean drinking water, clean streets and city-wide recycling programs. In 2009, UBS study of 73 world cities, Miami was ranked as the richest city in the United States and the world's fifth-richest city, in terms of purchasing power.
Downtown Miami and South Florida are home to the largest concentration of international banks in the United States, and is home to many large companies both nationally and internationally. The Civic Center is a major center for hospitals, research institutes, medical centers, and biotechnology industries.
For more than two decades, the Port of Miami, known as the "Cruise Capital of the World" has been the number one cruise passenger port in the world, accommodating some of the world's largest cruise ships and operations, and is currently the busiest in both passenger traffic and cruise lines.