Metropolitan Areas (1993)
The following maps were imported from Census data obtained from ftp://ftp.census.gov/pub/tiger/boundary/
1993 Metropolitan Areas (MA) - The Federal Office of Management and
Budget (OMB) designates and defines MAs. MAs include Metropolitan
Statistical Areas (MSAs), Consolidated Metropolitan Statistical Areas
(CMSAs), and Primary Metropolitan Statistical Areas (PMSAs), of which
MSAs are the most numerous. This boundary file contains only PMSAs
and MSAs. The underlying concept of an MSA is that of a core area
containing a large population nucleus, together with adjacent communities
having a high degree of economic and social integration with that core.
MSAs are composed of entire counties, except for New England, where the
component entities are MCDs. According to the OMB criteria , each MSA
must include either a city with at least 50,000 persons, or a Census Bureau-
defined urbanized area and a total population of at least 100,000 (75,000 in
New England). Within an area that meets the requirements to be an MSA
and also has a population of one million or more, the OMB recognizes
individual component areas if they meet specified criteria and local opinion
supports their recognition. If recognized, the component areas are
designated PMSAs, and the entire area that contains them becomes a
CMSA. If no PMSAs are recognized, the entire area is designated an MSA.
The boundary file contains PMSAs and MSAs recognized as of June, 1993,
although the actual boundaries of the areas are based on 1990 counties and
1990 MCDs. The PMSA/MSA geocode consists of a 4-digit Census code.