A metropolitan city, also known as a metro, is a region consisting of a densely populated urban agglomeration and its surrounding territories sharing industries, commercial areas, transport network, infrastructures, and housing. A metropolitan area usually comprises multiple principal cities, jurisdictions, and municipalities, such as neighborhoods, townships, boroughs, cities, towns, exurbs, suburbs, counties, districts, and even states and nations in areas like the eurodistricts. The U.S. Office of Management and Budget defines metropolitan areas as standardized county or equivalent-based areas having at least one urbanized area of 50,000 or more population, plus adjacent territory that has a high degree of social and economic integration with the core, as measured by commuting ties.
In the United States, a metropolitan city is defined as a city within a metropolitan area that is the central city of such area, as defined and used by the Office of Management and Budget, or any other city within a metropolitan area that has a population of fifty thousand or more. Any city that was classified as a metropolitan city for at least two years pursuant to the first sentence of this paragraph shall remain classified as a metropolitan city.
