An
area’s geographic
context has a significant effect on its development.
Economic opportunities
accrue to a place by virtue of both its size
and its access to larger economies. Population
size, urbanization, and access to larger communities
are often crucial elements in county-level
research. To advance such research, ERS developed
a set of county-level urban influence categories
that captures some differences in economic
opportunities.
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Large
metro: In areas with at least 1
million residents
Small metro: In areas with less than 1 million residents
Micropolitan: Areas containing an urban core of at least 10,000 residents
Noncore: Counties without an urban core of at least 10,000 residents |
The
2003 Urban Influence Codes divide the 3,141
counties, county equivalents, and independent
cities in the United States into 12 groups.
Counties are first
divided into metropolitan (metro) and nonmetropolitan (nonmetro) categories
according to the official classification announced by the Office of Management
and Budget (OMB) in June 2003, based on population and commuting data from
the 2000 Census of Population. Metro counties are then divided into two groups
by the size of the metro area they are in—large and small (see box, “County
Definitions”). Nonmetro counties are divided into 10 groups, first by
micropolitan (micro) versus noncore status, then by proximity to metro- or
micro-areas.
Nonmetro micro counties are divided into
three groups by their adjacency to metro areas—adjacent to a large metro area, adjacent to a small metro
area, and not adjacent to a metro area. Nonmetro noncore counties are divided
into seven groups by their adjacency to metro or micro areas and whether
or not they have their “own town” of at least 2,500 residents.
Nonmetro counties are defined as adjacent if they abut a metro area (noncore
counties may also abut a micro area) and have at least 2 percent of employed
persons commuting to work in the core of the metro area (or in the micro area).
When a nonmetro county was adjacent to more than one metro (or micro) area,
it was designated as adjacent to the area to which the largest percentage of
its workers commuted.
In concept, the 2003 Urban Influence Codes are comparable with those of earlier
decades. However, as a result of changes in metro area delineation procedures
and in rural and urban area measurement, our new codes are not fully comparable
with those of earlier years. Those changes are explained on the ERS website
at: www.ers.usda.gov/briefing/rurality/newdefinitions/.
2003
Urban Influence Codes |
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Metropolitan
counties:
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In
large area of at least 1 million residents
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In
small area of less than 1 million residents
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Nonmetropolitan
counties:
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Micropolitan
counties— |
Adjacent
to large metro
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Adjacent
to small metro
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Not
adjacent1
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Noncore
counties— |
Adjacent
to large metro
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Adjacent
to small metro with own town
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Adjacent
to small metro with no own town
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Adjacent
to micro with own town2
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Adjacent
to micro with no own town2
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Not
adjacent to metro or micro with own
town1
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Not
adjacent to metro or micro with no
own town
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Total
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1
Micro counties that are not adjacent
are often local trade centers. Nonadjacent-noncore
counties with towns may be service
centers for surrounding smaller counties,
especially in less-populated areas
of the Great Plains.
2 The micro area that a noncore county is adjacent to may itself be adjacent
to a small or large metro area. This hierarchical commuting relationship
is not reflected in the coding system.
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