Miami, officially the City of Miami, is the cultural, economic and financial center of South Florida, United States. Miami is the seat of Miami-Dade County, the most populous county in Florida. The city covers an area of about 56.6 square miles (147 km2), between the Everglades to the west and Biscayne Bay on the east; it is also the sixth most densely populated major city in the United States. The Miami metropolitan area is home to 6.1 million people and the seventh-largest metropolitan area in the nation. Miami's metro area is the second-most populous metropolis in the southeastern United States and fourth-largest urban area in the U.S.Miami is a major center, and a leader in finance, commerce, culture, media, entertainment, the arts, and international trade. The Miami Metropolitan Area is by far the largest urban economy in Florida and the 12th largest in the United States with a GDP of $344.9 billion as of 2017. In 2012, Miami was classified as an "Alpha−" level world city in the World Cities Study Group's inventory. In 2010, Miami ranked seventh in the United States and 33rd among global cities in terms of business activity, human capital, information exchange, cultural experience, and political engagement. In 2008, Forbes magazine ranked Miami "America's Cleanest City", for its year-round good air quality, vast green spaces, clean drinking water, clean streets, and citywide recycling programs. According to a 2009 UBS study of 73 world cities, Miami was ranked as the richest city in the United States, and the world's seventh-richest city in terms of purchasing power. Miami is nicknamed the "Capital of Latin America" and is the largest city with a Cuban-American plurality.Miami has the third tallest skyline in the U.S. with over 300 high-rises. Greater Downtown Miami has one of the largest concentrations of international banks in the United States, and is home to many large national and international companies. The Civic Center (Miami)|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. It accommodates some of the world's largest cruise ships and operations, and is the busiest port in both passenger traffic and cruise lines. Metropolitan Miami is also a major tourism hub in the southeastern U.S. for international visitors, ranking number two in the country after New York City.