Metropolitan Statistical Areas

Metropolitan Statistical Areas (MSAs) are a creation of the Office of Management and Budget and reflect 50 years of effort by the federal government to produce a uniform statistical framework. The general concept is that an area with a population nucleus and its adjacent communities have a high degree of integration and should often be considered as a statistical unit.

In the past, only large population centers were recognized and the primary focus was on the urban cores and surrounding areas. This is now changing somewhat as Micropolitan Statistical Areas have been recognized to allow statisticians to include smaller, more rural communities and population bases. This is not to say that the two categories are defined by a strict urban/rural line as both will almost certainly contain a urban/rural mix. Rather, the difference is determined by population and is broken down by the OMB as follows:

Metropolitan Statistical Area

A Core Based Statistical Area associated with at least one urbanized area that has a population of at least 50,000. The Metropolitan Statistical Area comprises the central county or counties containing the core, plus adjacent outlying counties having a high degree of social and economic integration with the central county as measured through commuting.

Micropolitan Statistical Area

A Core Based Statistical Area associated with at least one urban cluster that has a population of at least 10,000, but less than 50,000. The Micropolitan Statistical Area comprises the central county or counties containing the core, plus adjacent outlying counties having a high degree of social and economic integration with the central county as measured through commuting.

The federal government has names and categories for just about everything. If you are interested in exploring the nuances of the OMB’s naming scheme for statistical areas you may want to take a look at Standards for Defining Metropolitan and Micropolitan Statistical Areas.