1

Proposed Urban Area Criteria for the 2010 Census

Michael RatcliffeGeography Division U.S. Census BureauLet’s Focus on Census Geography WorkshopGIS-TApril 11, 2010

2

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.

3

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

4

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.

5

Census 2000 Basic Urban Core Delineation

6

Census 2000 Basic Urban Core Delineation

7

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.

Qualifying census tract ≥ 1,000 ppsm

Qualifying census tract ≥ 500 ppsm contiguous to initial coreCensus tract not contiguous to an initial core census tract ≥ 1,000 ppsmCensus tract > 3 sq. miles

Initial Census Tract Core Based on Population and Size Criteria

1,600 ppsm

1,300 ppsm

750 ppsm

550 ppsm

560 ppsm

700 ppsm

800 ppsm

Initial Core Using Census Tract Analysis Units

9

Cincinnati UA Qualifying Core Employment Tract

Employment TractsCensus 2000 Cincinnati UA

Qualifying census tract ≥ 1,000 wpsm

Qualifying census tract ≥ 500 ppsm contiguous to initial coreCensus tract not contiguous to an initial core census tract ≥ 1,000 wpsmCensus tract > 5 sq. miles and < 15 sq. miles

Initial Census Tract Core Based on Employment and Size Criteria

1,600 wpsm

1,300 wpsm

750 wpsm

550 wpsm

560 wpsm

15,000 workers

And

1,200 wpsm

800 wpsm

Initial Core Using Census Tract Analysis Units

Initial Core Test Delineation Regions

Tract as Analysis Unit Block Group as Analysis Unit

Population Land Area (sq. miles)

Number of Initial Urban Cores

Population Land Area (sq. miles)

Number of Initial Urban Cores

42,252,474 14,779 918 42,384,952 15,027 904

12

Splitting Large Urban Agglomerations

Census 2000 San Francisco-Oakland and San Jose Split

Commuting core A ≥ 50,000 persons

Commuting core B ≥ 50,000 personsLargest worker flow to commuting core A

No commuting association and largest adjacency with urban area B

Largest worker flow to commuting core B

Splitting Large Urban Agglomerations Using Commuting Patterns

Urban area A after split

Urban area B after split

Urban split

14

Concord/Livermore UA Split

15

2000 Urban Area ´Urban Area Boundary Using Impervious Land Cover

Impervious Land CoverCensus Blocks

0 0.2 0.40.1Miles

Boundary Using Proposed Impervious Criteria

Wetlands as an Additional Exempted Territory

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 jump distance is 3.2 miles

Urban Core

Noncontiguous qualifying territory

Jump census block

Road connection

Total exempted distance is 1.8 miles

17

5 0 5 10 Miles

Polygons w/slope greater than 40%Proposed 2010 Cumberland UA2000 Cumberland UAN

EW

S

Cumberland, MD and Surrounding Area

Exempted slope jumps

Steep Slope as Exempted Territory

Qualification of Airports for Inclusion in Urban Areas

Merced Municipal/MacCready Field, Merced CA

19

Prison Urban Clusters

Abilene North (Robertson Unit), TX Population: 4,650Urban: 4,650Group Quarters: 4,650Institutional: 4,650Correctional: 4,650Density: 94,589 ppsm

20

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.

21

Questions? Comments?

Vincent OsierChiefGeographic Standards and Criteria BranchGeography DivisionU.S. Census BureauVincent.osier@census.gov(301) 763-9039

Chris HenrieGeographic Standards and Criteria BranchGeography DivisionU.S. Census Bureauchristopher.j.henrie@census.gov(301) 763-9086