Introduction to Census Geography
The Census Bureau uses its own methods and terminology for geography, one of the most commonly used is the "Census tract" which divides up counties. The links on this page are provided to help users comprehend Census geography and how it can be used to better understand population and demographic data.
For a full explanation of the diagram, see the Hierarchy Diagrams page on the Census Bureau website.
Examples of Tracts, Block Groups and Census Blocks
Map of Census Tracts in Ann Arbor, Michigan
Map of Block Groups in Ann Arbor, Michigan
Map of Census Blocks in Ann Arbor, Michigan
What's my census tract or block group number?
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Social ExplorerUse the Maps feature in Social Explorer to explore the census maps. Click on the Find button (the binoculars) to enter an address and determine the tract number
Online Resources
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Census Bureau Geography ProgramCensus Bureau website with links to geographic data and products
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Geographic Areas Reference ManualReleased in 1994, this reference manual explains Census geography in detail, including definitions and procedures. Table 2-1 within the report is especially useful for hierarchically displaying the various geographic divisions as well as how many of each there are, as of the 1990 Census. Not that this report was released in 1994, so some data may have altered.
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Geographic Terms and ConceptsThis resource provides detailed explanations of Census geography, including Census tracts, Census blocks, Native American tribal areas, school districts, and others.
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State and County Subdivision Outline MapsPDFs from the U.S. Census Bureau displaying "counties, county subdivisions, places consolidated cities and American Indian areas/Alaska Native areas/Hawaiian home lands" by state. Also includes Puerto Rico, American Samoa, Guam, Northern Mariana Islands, and the U.S. Virgin Islands.
Last Updated: Dec 10, 2025 12:53 PM
Subjects: Government, Politics & Law