The OMB designates the largest city in each MSA or CMSA as a central city, and additional cities qualify for this designation if specified requirements are met concerning population size and commuting patterns. The central cities of a NECMA are those cities in the NECMA that qualify as central cities of an MSA or a CMSA.
The title of each MSA consists of the names of up to three of its central cities and the name of each State into which the MSA extends. However, a central city is not included in an MSA title unless it has at least one-third the population of the area’s largest city or local opinion supports its inclusion. Typically, titles of PMSAs also are based on central city names, but in certain cases consist of county names. Generally, titles of CMSAs are based on the titles of their component PMSAs, although CMSA titles may include suitable regional designations. NECMA titles are derived from the names of central cities. As is the case for MSAs, a CMSA, PMSA, or NECMA title always includes the names of all States into which the area extends.
In the period between decennial censuses, the OMB may define new MSAs and make certain other types of changes specified in the MA standards. Intercensal MA changes result from population counts or estimates from the Census Bureau. During the 1990s, research is under way to produce a new approach for defining areas using data from the 2000 census.
An area can qualify for intercensal designation as an MSA in three ways: (1) a city reaches the 50,000 population threshold according to a Census Bureau special census count or estimate; (2) a nonmetropolitan county (or group of counties) containing a UA from the most recent decennial census reaches the 100,000 population threshold according to a special census count or estimate (or, in New England, the cities and towns qualifying for the potential MSA reach the 75,000 threshold); or (3) the Census Bureau defines a new UA based on a special census, and the potential MSA containing this UA meets the above population requirements. If
