Introduction to Census Geography
Understanding Census geography is not always as simple as it would seem. there are traditional methods for dividing up geography in the United States that most people are familiar with, such as states, counties, and zip codes. The Census uses its own methods and terminology for geography as well, the most prominent of which is a division known as a "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.
The following image offers a basic outline of Census geographic divisions. 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
Census Tracts in Ann Arbor, Michigan
Block Groups in Ann Arbor, Michigan
Census Blocks in Ann Arbor, Michigan
What's my census tract or block group number?
- Social Explorer This link opens in a new windowUse 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
- Census Bureau Geography ProgramCensus Bureau website with links to geographic data and products
- 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.
- Geographic Terms and ConceptsThis resource provides detailed explanations of Census geography, including Census tracts, Census blocks, Native American tribal areas, school districts, and others.
- 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.
Print Resources
- Map Guide to the U.S. Federal Census, 1790-1920 bySee this guide for information on how Census geography has changed from the first Census through the early 20th Century. It is available in both a printed copy in the Map Library, as well as a limited preview version from Google Books.
Various maps and publications by the Geography Division of the U.S. Census Bureau are available in the Hatcher Graduate Map Library, as well as other libraries on campus, and electronically. Most of these publications are from the second half of the 20th century through the early 21st century. See Library Catalog Search for a full listing.
The books below are all print guides for Census geography available through the University library system.
- A Guide to State and Local Census GeographyPublished in 1993, this guide is available in the Government Documents Center Reference Room.
- Maps and More: Your Guide to Census Bureau GeographyPublished in 1994, this book is available in the Hatcher Graduate Map Library.