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The U.S. Decennial Census

A guide to the U.S. Census that is done every 10 years (Decennial)

Geography Basics

To search for and locate current Census data, it helps to have a basic understanding of the geographic areas used by the Census Bureau to gather and tabulate information. Geographic areas range from the largest (Nation) to the smallest (Block).   Census data is also presented for "geographies within geographies," such as Counties within a State, or Blocks within a Census Tract.

Geographic Hierarchy

The Census Bureau uses a geographical hierarchy to organize its data, as illustrated by the graphic below:

More information about Census geography

For additional information, refer to Guidance for Geography Users

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