Metropolitan division

A county or group of counties within a core based statistical area (metropolitan statistical area) that contains a core with a population of at least 2.5 million. A metropolitan division consists of one or more main/secondary counties that represent an employment center or centers, plus adjacent counties associated with the main county or counties through commuting ties.

We use the most current definitions available from the Office of Management and Budget (OMB) and carry them through the entire time series.

For more information on how metropolitan areas are defined, see

A list of metropolitan areas and component counties is available.