Cities in America have sprawled so much that researchers call them “metropolitan statistical areas,” or MSAs. Urban areas are less based on exact city boundaries and more on density to include a wide swath of surrounding suburbs. U.S. federal agencies define metropolitan areas as those with a “core” of more than 50,000 people. That could be a city, or a larger area covering several counties in a state. Specifically, the U.S. Census Bureau also recognizes urban “clusters” that include areas that have at least 2,500 but less than 50,000 people. The New York-Newark area is the nation’s most populated urban area, according to the 2010 Census, followed by the Los Angeles-Long Beach-Anaheim area, and the Chicago area.
