Page:Geographic Areas Reference Manual (GARM).pdf/306

 that is urban. MSAs in New England are defined in terms of cities and towns, following rules concerning commuting and population density.

An area that meets the requirements to qualify as an MSA and also has a population of one million or more becomes a CMSA if component parts of the area are recognized as PMSAs.

Subareas may be defined within an area that meets the requirements to qualify as an MSA and also has a population of one million or more. The definition of these subareas, called PMSAs, requires meeting specified statistical criteria and having the support of local opinion. A PMSA consists of a large urbanized county or a cluster of counties (cities and towns in New England) that demonstrate strong internal economic and social links in addition to close ties with the central core of the larger area. Upon the recognition of PMSAs, the entire area of which they are parts becomes a CMSA. All territory within a CMSA is also within some PMSA.

NECMAs are county-based alternatives to the city- and town-based MSAs and CMSAs in the six New England States. The county composition of a NECMA reflects the geographic extent of the corresponding MSA(s) or CMSA(s). NECMAs are not defined for individual PMSAs.

Interest in developing a consistent definition of metropolitan dates back more than a century. The metropolitan concept arose from the common observation that the physical extent of a large urban concentration often overflows the official limits of any single city. The existence of suburban territory outside the limits of important cities was noted in statistical Notes and References 13-2Metropolitan Areas