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Census & Metropolitan Definitions. Arthur C. Nelson, Ph.D., FAICP Presidential Professor & Director Metropolitan Research Center January 2010. Census Building Blocks. Census Tracts Census Blocks Census Block Groups County Subdivisions Traffic Analysis Zones. Census Tracts.
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Census & Metropolitan Definitions Arthur C. Nelson, Ph.D., FAICP Presidential Professor & Director Metropolitan Research Center January 2010
Census Building Blocks • Census Tracts • Census Blocks • Census Block Groups • County Subdivisions • Traffic Analysis Zones
Census Tracts Small, permanent county statistical subdivisions. Census tract boundaries normally follow visible features, but may follow governmental unit boundaries and other non-visible features, and they always nest within counties. Census tracts designed to be relatively homogenous units with respect to population characteristics, economic status, and living conditions of creation. They usually contain 1,500 to 8,000 people and average about four block groups. There are about 66,000 tracts nationwide.
Census Blocks Census Blocks are the smallest entity for which the Census Bureau collects and tabulates census information (SF 1 only). There are about 8.5 million blocks nationwide.
Census Block Groups Block Groups are a combination of census blocks and are also a subdivision of census tracts. Block groups generally contain between 600 and 3000 people and are made up of on average 40 census blocks. There are about 211,000 block groups nationwide.
Traffic Analysis Zones A TAZ is a special area delineated by state and/or local transportation officials for tabulating traffic-related data and usually consists of one or more census blocks, block groups, or census tracts.
County Subdivisions County subdivisions are the primary divisions of counties for the reporting of decennial census data. Minor civil divisions (MCDs) are the primary governmental or administrative divisions of a county such as boroughs, towns, and townships. Census county divisions (CCDs) established by the Census Bureau in 21 states where there are no legally established MCDs.
Urban Areas • Densely settled area with minimum population of 2,500 people and minimum density of 5,000 persons square mile. • 2000 = 3,756 urban areas.
Urbanized Area • Densely settled core of census block groups and surrounding census blocks > 1,000 persons per square mile and 500 persons per square mile around it. • Densely settled blocks usually must accumulate to 50,000 people. • 2000 = 464 urbanized areas.
Urban Clusters • Scaled-down version of urbanized area where densely-settled census blocks accumulate to 2,500 to 50,000 people. • 2000 = 3,112 urban clusters.
Urban Population • All people living in urbanized areas and urban clusters. • 2000 = 79 percent of population.
Core Based Statistical Area –CBSA • Each CBSA contains at least one urban area with at least 10,000 people: • Urbanized area • Urban cluster • Includes outlying areas where 25% of workers work in a central county or multiple central counties combined. • Designated as either metropolitan or micropolitan area. • 2000 = 93 percent of population
Metropolitan & Micropolian Areas • Metropolitan areas include as least one urbanized area with at least 50,000 people. • 2000 = 361 metropolitan statistical areas • Micropolitan areas have at least one urban cluster between 10,000 and 50,000 people. • 2000 = 559 micropolitan areas