United States metropolitan area

In the United States, the Office of Management and Budget (OMB) has produced a formal definition of metropolitan areas. These are referred to as "Metropolitan Statistical Areas" (MSAs) and "Combined Statistical Areas." An earlier version of the MSA was the "Standard Metropolitan Statistical Area" (SMSA). MSAs are composed of counties[1]. In New England, because of the greater importance of towns over counties, similar areas based on town units, known as New England City and Town Areas (NECTAs), are additionally defined.
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