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Finding Census 2000 Data by Census Block

Jump to: What Are Tracts, Blocks & Block Groups? / Find & Map a Census Block /Find Data about a Census Block / Citing Data

Census Tracts, Blocks, & Block Groups (plus other Census definitions)

What is a Census Tract?

A census tract is a small statistical subdivision of a county. Census tract data allows a user to find population and housing statistics about a specific part of an urban area from both 100-percent data and sample data. (See Census Overview for a list of 100 percent topics and those that are only available in the sample data). Census tracts are particularly important when you want information about part of a city, such as Northridge or other communities in the San Fernando Valley which are part of the City of Los Angeles. A single community may be composed of several census tracts; there may be hundreds of census tracts in a large city.

What is a Census Block?

A census block is a subdivision of a census tract. In Census 2000, a census block is the smallest geographic unit for which the Census Bureau tabulates 100-percent data such as Age, Hispanic or Latino Origin, Race, Sex, Household Relationship, and whether Homeowners or Renters. Many census blocks correspond to individual city blocks bounded by streets, but this is not always true; blocks - especially in rural areas - may include many square miles and may have some boundaries that are not streets.

What is a Block Group?

In Census 2000, a block group is part of a census tract. A census tract may have one or more block groups within it; a block group usually consists of several census blocks within the same tract. So, a block group is geographically smaller than a census tract, but larger than a census block. A block group is the smallest geographic unit for which the Census Bureau tabulates sample data. (That means statistics based on sample data--statistics about income, education, citizenship, etc.--are only available for block groups and larger geographies; sample data is not available for a census block). A block group consists of all the blocks within a census tract with the same beginning number.

Definitions of other terminology used in the census:

Finding Census 2000 Block Data using American Factfinder

For your convenience, you may wish to print this set of step-by-step instructions before you begin. Also, the Census Bureau advises users that pop-up blocker software may affect American Factfinder in unusual ways. So, if you use a pop-up blocker, make sure it is turned off when you use American Factfinder.

Find the census tract, block group, and block numbers

To find block-level data, you first need to know the identifying numbers assigned by the Census Bureau for the census tract and block group in which the census block of interest is located as well as the identifying number of the census block itself. There are several ways to find these identifying numbers. An easy way to find them online is to use a street address (including the zip code--if you do not know the zip code, use Zip Code Lookup to determine it) of a site within the block of interest and follow the instructions below:

  1. Go to Address Search, an advanced geography search option in American FactFinder that allows you to enter a specific street address and zip code to create a map with boundaries from the 2000 Census and/or link to some of the data for geographic areas including that address.
  2. Verify that the Select a Year and Program pull-down menu is set for Census 2000.
  3. Input the address, including the zip code, in the appropriate boxes and click on Go. A list of geographies including that address will display. Write down the census tract number, the block group number, and the block number as you will need these to find your data.
  4. Click on Block (which will be followed by the block number) so that the row is highlighted.
  5. Click on Map It; a pop-up with a map of the block will appear.
  6. Examine the map to ensure that it is a map for the address you requested. If it is, you are ready to use the census tract number, block group number, and census block number (these appear at the top of the map if you failed to write them down earlier) to find data about your census block using the next set of instructions. (Note: Use the Print button on the screen or your browser's Print command if you wish to print the map so you have a record of the block boundaries).

Instructions to find Census Block-level data using American Factfinder Data Sets

  1. Go to American FactFinder.
  2. Select Data Sets (in the menu on the left side of the page) by clicking on it.
  3. The default selections the computer usually chooses are Decennial Census and Census 2000, which are the choices you want. Make sure that those are the choices selected. (If not, choose Decennial Census, then click on the tab for Census 2000).
  4. Make sure that Summary File 1 has a dot in the circle to the left of it. (If it was not the default selection for you, click on the circle to the left of it so that a dot appears in the circle). For Census 2000, Summary File 1 is the file that has census block level data. (Block level data is available on Census 2000 shortform (100 per cent) subjects. Census Overview includes a list of the topics that were 100 per cent subjects. Questionnaires provides an opportunity to see the questionnaires used).
  5. A menu will appear to the right of your choice. Select Detailed Tables.
  6. Make sure the selection method tab is on "list". (The selected tab will be on top; click on list if it isn't already selected).
  7. Select a geographic type by pulling down the menu and selecting Block.
  8. Select a state using the pull-down menu.
  9. Select a county using the pull-down menu.
  10. Wait for the list of census tracts in the county to appear and finish loading. Then use the pull-down menu and select your tract number by clicking on it. (Note: if you select your tract before the list is done loading, you may not be able to do the next step without reloading the page and repeating this step with more patience).
  11. Use the next pull-down menu to select the block group.
  12. Use the next pull-down menu to select the block number.
  13. Click on Add. Your block number should appear in the box under the Add button. (Note: if you need data on several different blocks, repeat the above steps until all the blocks you want have been added to the box).
  14. Click on Next.
  15. Choose a search method (by subject, by keyword, or show all tables). If you choose "by subject" or "by keyword", you will next have to search to get a list of tables that meet your criteria. (A box will ask you to type in a keyword or choose from a pull-down menu of stubjects and there will be a button labelled Search). If you choose "show all tables", a list of tables will appear in the box under the search method choice area.
  16. Select one or more tables by clicking on the one you want or highlighting several at the same time. (Note: If you want to choose several tables at the same time but the tables you want are not next to each other on the list, hold down your control (PC) or command (Mac) key while you click on the tables you want. This enables you to make discontinuous multiple selections).
  17. Click the Add button. The table names you selected should appear in the box under the Add and Remove buttons.
  18. Click on the Show Result button that is near the bottom of the screen (in the middle or on the right side of the screen); if necessary scroll over until it is displayed on your screen.
  19. Note: It is possible to ask for more data than the system can give you at one time. If you get a message that your request is too large, break your request into more than one search, each of which requests less data (i.e. request fewer tables or fewer geographic areas at the same time). The Remove button allows you to delete some of the tables you requested from the list of those to be shown.
  20. Printing: Data tables can be wider than a normal page of print; be forewarned that most users need to change the print properties/settings to print in landscape orientation (rather than portrait) to ensure that all data is printed.

Citing the Data

For suggestions on how to cite data from American Factfinder, use the Search box on the Census Bureau homepage. Choose to search FAQs, type American Factfinder Citations in the box, and click the Go button; this will provide access to a page on how to cite tables and maps from American Factfinder. Use Online Citation Style Guides or ask at the reference desk if you have any questions about how to cite your sources for your paper correctly following the rules for MLA and other frequently used styles.

Created and maintained by Mary M. Finley
Questions or comments: mary.finley@csun.edu
Links checked: 22 April 2008

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