Proposed Urban Area Criteria for the
2010 Census
Michael Ratcliffe
Geography Division
U.S. Census Bureau
Let’s Focus on Census Geography Workshop
GIS-T
April 11, 2010
1
Urban and Rural Classification
• The Census Bureau identifies and classifies urban and rural
areas after each decennial census.
• Urban areas of at least 2,500 people have been identified since
1906.
• Urbanized areas of 50,000 or more people were first defined for
the 1950 Census. Urban places of at least 2,500 people were
identified outside urbanized areas. Urban clusters of 2,500 49,999 were first defined after Census 2000.
• The Census Bureau
identifies urban and rural
areas solely for the
purpose of tabulating and
presenting statistical data.
2
Urban Area Definitions
• Represent densely developed territory, encompassing
residential, commercial, and other non-residential
urban land uses in which social and economic
interactions occur.
• Represent the “Urban Footprint”
• Structure has been explicitly defined through
measures based primarily on population counts
and residential population density
• Criteria have also accounted for non-residential
urban land uses that are functionally part of the
urban landscape
3
Census 2000 Urban Areas
•
For Census 2000, an urban area consists of a
densely settled core created from census block
groups, census blocks, and the adjacent densely
settled surrounding territory that together have a
minimum population of 2,500 people
•
Two types of urban areas:
•
urbanized areas of 50,000 or more population;
•
urban clusters of 2,500 – 49,999.
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Census 2000 Basic Urban Core Delineation
5
Census 2000 Basic Urban Core Delineation
6
2010 Urban Area Program
•
Remain committed to an objective, equitable, and consistent
nationwide urban area delineation.
•
Retain decennial comparability by building upon 2000 criteria.
•
All potential modifications are refinements, or supplements to
address deficiencies encountered for Census 2000.
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Initial Core Using Census Tract Analysis Units
Qualifying census
tract ≥ 1,000 ppsm
560
ppsm
800
ppsm
Qualifying census
tract ≥ 500 ppsm
contiguous to initial
core
Census tract not
contiguous to an initial
core census tract ≥
1,000 ppsm
550
ppsm
Census tract > 3 sq.
miles
1,600
ppsm
1,300
ppsm
700
ppsm
750
ppsm
Initial Census Tract
Core Based on
Population and Size
Criteria
Cincinnati UA Qualifying Core
Employment Tract
Census 2000 Cincinnati UA
Employment Tracts
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Initial Core Using Census Tract Analysis Units
Qualifying census
tract ≥ 1,000 wpsm
560
wpsm
800
wpsm
Qualifying census
tract ≥ 500 ppsm
contiguous to initial
core
Census tract not
contiguous to an initial
core census tract ≥
1,000 wpsm
550
wpsm
15,000 workers
Census tract > 5 sq.
miles and < 15 sq.
miles
1,600
wpsm
1,300
wpsm
And
1,200 wpsm
750
wpsm
Initial Census Tract
Core Based on
Employment and Size
Criteria
Initial Core Test Delineation Regions
Tract as Analysis Unit
Population
42,252,474
Land Area
(sq. miles)
14,779
Block Group as Analysis Unit
Number of
Initial
Urban
Cores
918
Population
42,384,952
Land Area
(sq. miles)
15,027
Number of
Initial
Urban
Cores
904
Splitting Large Urban Agglomerations
Census 2000 San Francisco-Oakland and
San Jose Split
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Splitting Large Urban Agglomerations Using Commuting Patterns
Commuting core A ≥
50,000 persons
Commuting core B ≥
50,000 persons
Largest worker flow to
commuting core A
Urban
area A
after
split
Largest worker flow to
commuting core B
No commuting
association and
largest adjacency
with urban area B
Urban
split
Urban
area B
after
split
Concord/Livermore UA Split
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Boundary Using Proposed Impervious Criteria
Urban Area Boundary Using Impervious Land Cover
2000 Urban Area
Impervious Land Cover
Census Blocks
´
0
0.1
0.2
0.4
Miles
15
Wetlands as an Additional Exempted Territory
Noncontiguous qualifying
territory
Jump census block
Urban Core
Road connection
Distance from core to
wetlands is 0.7 mile
Distance over
wetlands is 0.5 mile
Distance over
river is 0.6 mile
Distance over
wetlands is 0.7 mile
Distance from wetlands to
noncontiguous qualifying
area is 0.7 mile
Total
exempted
distance
is 1.8
miles
Total
jump
distance
is 3.2
miles
Steep Slope as Exempted Territory
Cumberland, MD and Surrounding Area
Exempted slope jumps
5
0
N
W
E
S
5
10 Miles
2000 Cumberland UA
Proposed 2010 Cumberland UA
Polygons w/slope greater than 40%
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Qualification of Airports for Inclusion in Urban
Areas
Merced Municipal/MacCready Field, Merced CA
Prison Urban Clusters
Abilene North (Robertson Unit), TX
Population: 4,650
Urban: 4,650
Group Quarters: 4,650
Institutional: 4,650
Correctional: 4,650
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Density: 94,589 ppsm
Central Places
• Central places are not necessary for UA or UC
delineation
• Principal cities defined within CBSAs:
• capture same concept
• classification based on different criteria
• Lack of consideration of place boundaries in
delineation process results in central places split
between urban and rural portions.
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Questions? Comments?
Vincent Osier
Chief
Geographic Standards and Criteria Branch
Geography Division
U.S. Census Bureau
Vincent.osier@census.gov
(301) 763-9039
Chris Henrie
Geographic Standards and Criteria Branch
Geography Division
U.S. Census Bureau
christopher.j.henrie@census.gov
(301) 763-9086
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