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Research Guides

U.S. Decennial Census: Defining Your Community for Census Research

Decade by decade information about how to access and use U.S. Census reports.

Defining your Community

The most difficult part of defining your Census geography is figuring out how Census designated geographies overlay with the streets and neighborhoods we know from everyday life.

You will need to determine what Census tracts, block groups, and blocks best match up with your community to find the Census data you need. These boundaries may not match up exactly with the official boundaries of your community, but using street maps and Census tract and block maps you will be bale to define and area that will work best for your research.

Identifying Census Tracts to find Neighborhood Statistics walks through the steps of finding Census tracts associated with your neighborhood. While this includes some Seattle-specific resources and neighborhood maps, the same principles can be applied to any city.

The Seattle Neighborhood Maps on the City of Seattle's website will help you identify the generally accepted street boundaries for Seattle neighborhoods.

For detailed street maps, check out the Thomas Guide King, Pierce, and Snohomish Counties street guide in the library or use a web-based mapping tool, such as Google Maps.

For detailed online Census tract, block group, and block information for 1990 and 2000, you can use the Census Bureau Reference Maps or use the mapping applications in Explore Census Data. If you only need Census tract information, Social Explorer is a great option. Social Explorer does not identify blocks or block groups, but does include streets and is an excellent way to quickly compare tract boundaries over time.

The Maps for 2000 are available in the library. For earlier years, look for the maps in the Census tract and block volumes. Maps are usually included in a back book pocket or a separate folio shelved next to the volume.

Census tract numbers and boundaries may change over time. Check all your Census years before making a final decision on community boundaries. Remember, the farther back in time you go, the larger your Census tracts are likely to be.

The City of Seattle has developed several dozen Community Reporting Areas (CRA).

Tracts & Blocks in Seattle

The 2010 Census Tract Reference Map for King County, WA with Census tract numbers written in red.

Image courtesy of the U.S. Census Bureau.


Need help? Call the Government Publications, Maps, Microforms & Newspapers help desk at (206) 543-4164 during desk hoursYou can also consult the 24/7 Ask Us! reference service.