Census Guide

Rechs Ann Pedersen, Internet Librarian
Last updated 5/1/2001

Tracts and Blocks: Data and Maps

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Tract and Block Data || Identifying the Tract or Block for an Area || Sources of Tract and Block Maps

Tracts are areas within a county. They do not necessarily match up with any other type of boundary--cities, CDPs, zip codes, etc. You need to look at the Tract Maps to see how tracts relate to other areas.Tracts are numbered using four digits (ex. 1204) or four digits, a decimal, and two digits (ex. 1205.98).

Blocks are subdivisions within a tract.They are the smallest geographical areas used in the Census. Not all data tabulations are available for Blocks because it could lead to revealing confidential information about individuals in that area. Blocks are numbered using 3 digits (ex. 423) in the 1990 Census and 4 digits in the 2000 Census.

Finding tract and block data is a two step process.

1. Identify the tracts or blocks that include the area you want. (see the sections below) For tracts, note the tract number. For blocks, note both the tract number and the block numbers.
2. When you know the numbers, go to a source with the tract and block data
   Some online sources for identifying or showing a tract will give some tract data. But these sources may be limited. If the statistics given aren't what you want, try a straight data source. (see Sources for Finding the Data)

FOR AN AREA

If you want the tract or block numbers that comprise an area or place, you need to look at Tract and Block maps (see below: Sources of Tract and Block Maps). Since street names are not always indicated for tracts and not indicated at all for place boundaries, you may need to use a street map at the same time. To get starting reference points, you can use one of the sources under "For a Street" to find the tract or block numbers for particular streets in the area that you want.

FOR A STREET

2000 Census

• Use the Advanced Geography Selection search form on the U.S. Census Bureau Website. Select "address" and then type the location information. The results will give the tract and block numbers. Either select one or more of the choices for the information online or note the numbers and use them in other sources.
• Find tract and block numbers from the Tract or Block Maps. (see below: Sources of Tract and Block Maps)

1990 Census

• Use the paper Tract and Block maps, which are available at the Reference Desk at the Central Branch. Also at the Reference Desk is "1990 TIGER/Census Tract Street Index," which lists City of Santa Cruz streets and tells which tracts contain them.
• Online Tract Search from Census Bureau called, Census Tract Street Locator Searched by combination of street name and zip code. Gives tracts by name of street. Does not show location of the tract. Links to Sample Data (STF3A) for the tract with option to see data for other tracts in County. If you want only 100% data, do not use the sample data, use another source (see Sources for Finding Data)

Note: Since street names are not always indicated for tracts and not indicated for place boundaries, you may need to have a street map handy.

2000 Census:

Santa Cruz County:

• Online Tract and Block Maps for Santa Cruz Country are available on this Website.
• Paper tract and block maps for Santa Cruz County are available at the following Branch Libraries: Aptos, Central and Scotts Valley.

All of the United States (incl. Santa Cruz):

• Online tract maps are available for all U.S. counties. They are in pdf format from the Census Bureau at Index of /plmap/pl_trt. Select the State directory that you want, then the county. Displays links to tract maps in pdf.
• Online block maps are available for U.S. counties. They are in pdf format from the Census Bureau at Index of /plmap/pl_blk Select the State directory that you want, then the county. Displays links to block maps in pdf.
• American FactFinder's Reference Maps is an interactive map that allows you to zoom in and select features to view.

1990 Census:

Santa Cruz County:

• Paper Census 1990 Tract and Block maps are available at the Reference Desk at the Central Branch.

All of the United States:

• Online from American FactFinder can be used to show tracts (without numbers) and other geographical features. A limited selection of data can be displayed as a colored map. (Choose from either STF 1 (100% data), or STF 3 (Sample data).

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