2000 Rural-Urban Commuting Area Codes
The Rural-Urban commuting area (RUCA) codes, a detailed and flexible
scheme for delineating sub-county components of the U.S. settlement
system, have been updated using data from the 2000 decennial census.
RUCA codes are based on the same theoretical concepts used by the
Office of Management and Budget (OMB) to define county-level metropolitan and micropolitan areas. We applied similar criteria to measures
of population density, urbanization, and daily commuting to identify
urban cores and adjacent territory that is economically integrated
with those cores. We adopted OMB’s metropolitan and micropolitan
terminology to highlight the underlying connectedness between the
two classification systems. However, the use of census tracts instead
of counties as building blocks for RUCA codes provides a different
and more detailed geographic pattern of settlement classification.
Census tracts are used because they are the smallest geographic
building block for which reliable commuting data are available.
The classification contains 10 primary and 30 secondary codes.
Few, if any, research or policy applications need the full set
of codes. Rather, the system allows for the selective combination
of codes to meet varying definitional needs.
The 10 whole numbers shown in Table
1 below refer to the primary,
or single largest, commuting share. Metropolitan cores (code 1)
are defined as census tract equivalents of urbanized
areas. Micropolitan
and small town cores (codes 4 and 7, respectively) are tract equivalents
of urban clusters. Tracts are included in urban cores if more than
30 percent of their population is in the urbanized area or urban
cluster.
High commuting (codes 2, 5, and 8) means that the largest commuting
share was at least 30 percent to a metropolitan, micropolitan,
or small town core. Many micropolitan and small town cores themselves
(and even a few metropolitan cores) have high enough out-commuting
to other cores to be coded 2, 5, or 8; typically these areas are
not job centers themselves but serve as bedroom communities for
a nearby, larger city. Low commuting (codes 3, 6, and 9) refers
to cases where the single largest flow is to a core, but is less
than 30 percent. These codes identify "influence areas" of
metro, micropolitan, and small town cores, respectively, and are
similar in concept to the "nonmetropolitan adjacent" codes
found in other ERS classification schemes (Rural-Urban
Continuum Code, Urban
Influence Code). The last of the general classification
codes (10) identifies rural tracts where the primary flow is local
or to another rural tract.
These 10 codes offer a relatively straightforward
and complete delineation of metropolitan and nonmetropolitan settlement
based
on the size and direction of primary commuting flows. However,
the settlement world is not that simple. The primary RUCA codes
are further subdivided to identify areas where settlement classifications
overlap, based on the size and direction of the secondary, or
second largest, commuting flow. For example, 1.1 and 2.1 codes
identify
areas where the primary flow is within or to a metropolitan core,
but another 30 percent or more commute to a larger metropolitan
core. Similarly, 10.1, 10.2, and 10.3 identify rural tracts for
which the primary commuting share is local, but more than 30
percent also commute to a metropolitan, micropolitan, or small
town core, respectively.
Influence areas for urban cores extend far beyond the relatively
small number identified on the basis of primary flows (codes
3, 6, and 9). Codes 4-10 were subdivided to identify micropolitan,
small town, and rural tracts with secondary flows of 10 to 30
percent to larger urban cores. This strategy identifies important,
potentially urbanizing zones within current nonmetropolitan
territory.
RUCA codes are many, but permit stricter or looser delimitation
of metropolitan, micropolitan, and small town commuting areas.
This classification scheme provides an alternative to county-based
systems for situations where more detailed geographic analysis
is feasible. It identifies areas of emerging urban influence
and areas where settlement classifications overlap, thus
providing an exhaustive system of statistical areas for the
country.
Table 1. Rural-Urban Commuting Areas (RUCAs),
2000
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1 Metropolitan area core: primary
flow within an urbanized area (UA)
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1.0
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No additional code |
|
|
1.1
|
Secondary flow 30% to 50% to a larger UA |
|
|
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|
2 Metropolitan area high commuting:
primary flow 30% or more to a UA
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|
2.0
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No additional code |
|
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2.1
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Secondary flow 30% to 50% to a larger UA |
|
|
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|
3 Metropolitan area low commuting:
primary flow 5% to 30% to a UA
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|
3.0
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No additional code |
|
|
|
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4 Micropolitan area core: primary flow within
an Urban Cluster of 10,000 to 49,999 (large UC)
|
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4.0
|
No additional code |
|
|
4.1
|
Secondary flow 30% to 50% to a UA |
|
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4.2
|
Secondary flow 10% to 30% to a UA |
|
|
|
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5 Micropolitan high commuting: primary flow
30% or more to a large UC
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|
5.0
|
No additional code |
|
|
5.1
|
Secondary flow 30% to 50% to a UA |
|
|
5.2
|
Secondary flow 10% to 30% to a UA |
|
|
|
|
6 Micropolitan low commuting: primary flow
10% to 30% to a large UC
|
|
6.0
|
No additional code |
|
|
6.1
|
Secondary flow 10% to 30% to a UA |
|
|
|
|
7 Small town core: primary flow within an
Urban Cluster of 2,500 to 9,999 (small UC)
|
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7.0
|
No additional code |
|
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7.1
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Secondary flow 30% to 50% to a UA |
|
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7.2
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Secondary flow 30% to 50% to a large UC |
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7.3
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Secondary flow 10% to 30% to a UA |
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7.4
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Secondary flow 10% to 30% to a large UC |
|
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8 Small town high commuting: primary flow
30% or more to a small UC
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8.0
|
No additional code |
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8.1
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Secondary flow 30% to 50% to a UA |
|
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8.2
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Secondary flow 30% to 50% to a large UC |
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8.3
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Secondary flow 10% to 30% to a UA |
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8.4
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Secondary flow 10% to 30% to a large UC |
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9 Small town low commuting: primary flow
10% to 30% to a small UC
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9.0
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No additional code |
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9.1
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Secondary flow 10% to 30% to a UA |
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9.2
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Secondary flow 10% to 30% to a large UC |
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10 Rural areas: primary flow to a tract
outside a UA or UC
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10.0
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No additional code |
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10.1
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Secondary flow 30% to 50% to a UA |
|
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10.2
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Secondary flow 30% to 50% to a large UC |
|
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10.3
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Secondary flow 30% to 50% to a small UC |
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10.4
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Secondary flow 10% to 30% to a UA |
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10.5
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Secondary flow 10% to 30% to a large UC |
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10.6
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Secondary flow 10% to 30% to a small UC |
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A ZIP code approximation of the RUCA codes is also available.
It is based on an overlay of ZIP code areas on
census tracts and not on a separate analysis of population and
commuting data unique to the ZIP code geographic unit.
This research was sponsored and funded by ERS and the Health Resources
and Services Administration's Federal Office of Rural Health Policy
(ORHP), and executed at the WWAMI Rural Research Center at the University
of Washington. For further information, see Morrill, Richard, John
Cromartie, and Gary Hart. 1999. "Metropolitan, Urban, and Rural
Commuting Areas: Toward a Better Depiction of the United States
Settlement System." Urban Geography 20: 727-748.
Download the 2000
or 1990 Rural-Urban Commuting Area Codes
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