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Census Basics: Geography

summary of important basic information on finding and using Census data

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Census Geography Basics

Different items of data are available for different units of geography. Simply put:

The smaller the geographical area, the fewer items of data are available

​Some more tips:

  • Rather than worry about distinctions between "city" and "town," all such entities are called Census Places or just Places. Non-incorporated areas are given names as Census Designated Places.
  • Sometimes customary names for places and areas (for example, names of post offices) might not correspond with a legal place boundary. And even legal place boundaries might not correspond exactly with Census geography.
  • The Census Bureau tries to follow local geography when designating their geographical entities, but they do have a number of Census-created geographic areas. For a discussion of legal vs. statistical geography, see this box.

TX flagFor help with Texas geographies, here are some resources from the Texas Demographic Center (formerly the State Data Center).

More about Census Geography: Terms

USAHere are some major Census geographical terms and tips for using them. For more information, see this box and for even more, see Geographic Terms and Concepts at Census.gov.

  • Census Tracts. 
    • ​smallest areas for which details on the population are taken (income, education, etc.)
    • you need a tract number to find data for an area; see this box
    • relatively stable geographic units that have between 1200 and 8000 people
    • may roughly correspond to a neighborhood in some areas
    • lie completely within county boundaries 
    • beginning with the 2000 Census, they cover the entire country
  • Blocks.
    • smallest area for which the Census reports data
    • you need a block number to find data; use the "Address Search" function at American FactFinder
    • only basic data is available at the Block level 
    • in cities, a Census Block conforms with what is usually thought of as a block
    • in rural areas, Census Blocks are bounded by visible features such as streams, transmission lines, etc.
  • Place.
    • generic name for cities, towns, boroughs, and villages.
    • city boundaries might not always match reality on the ground. 
    • Census Designated Place is a settled concentration of population not legally incorporated
  • Metropolitan Area (MA). 
    • ​include a large city or cities, with their surrounding suburbs.
    • key point is that the suburbs are closely integrated, socially and economically, with the central city
    • terminology has varied over time on this topic
  • States/Counties. These geographical areas are [thankfully] not modified by the Census Bureau, but retain their normal definitions and boundaries.

cityHere are some more terms dealing with urban areas:

  • Urbanized areas.  Areas where there is population-based impact on the landscape, largely based on population 
    • Urban Areas have 50,000 or more inhabitants
    • Urban Clusters are smaller, more rural areas that contain from 2500 to 50,000 people.
    • Metropolitan counties have Urban Areas within their boundaries
    • Micropolitan counties have an Urban Cluster within them, but not an Urban Area
  • Zip Code Tabulation Area (ZCTA). 
    • areas that approximate Postal Service 3- and 5-digit Zip Code areas
    • generally speaking, demographic Census data is not available by Zip Code, but by ZCTA
    • ​however, some Economic Census data is available by Zip Code