Census data is collected, displayed and analyzed by way of maps. This section will provide you with information on how census data is collected and stored, obtained and used, and also helpful resources for you to find additional information.
Spatial data and the TIGER Database:
• What is TIGER and how was it created?
• When will the latest TIGER files be available?
• How can I use TIGER data?
• More Information
Statistical Data and On-Line Mapping:
• How is data collected?
• How can I view data?
• When will the Census 200 data be available?
What is TIGER and how was it created?
In advance of 1990, spatial data for the entire country were assembled into a digital form, creating TIGER (Topologically Integrated Geographic Encoding and Referencing). TIGER is a database of features which are described by geographic coordinates. The topological structure of the database describes the areas for which census data is collected, location and relationship of streets, rivers, lakes, political boundaries, railroads, and other geographic features to each other. TIGER does not include demographic statistics.
To create the TIGER database, a number of materials were used. Existing 1:100,000 scale USGS topographic maps for the entire United States were scanned as thematic layers into digital form and delivered to the Census Bureau. The USGS scanned the roads, railroads, hydrographic features and transportation layers, which were then vertically integrated into one database. For major urban areas GBF/DIME files (created in the 1970 and 1980 census) were substituted. The resulting database was updated based on local maps as well as fieldwork done by the Census Bureau.
Because of limited content of the 1:100,000 scale maps from which they were created, the TIGER line files are a generalized view of the features. Many smaller features are not included, and the position and shape of those that are not as accurate as in some other maps/databases. Nevertheless, TIGER files have many uses. Like other federal government information, the TIGER line files are not copyrighted. As a result, numerous private companies have repacked the data in various value-added forms. Return to Top When will the latest TIGER files be available? Return to Top How can I use TIGER data? A number of products are available on CD-ROM at a range of prices, from the Census Mapper (free) to the TIGER/Census Tract Street Index ($150 per CD). More information on these products can be found by contacting Census Bureau Customer Service. Return to Top More information Return to Top
Statistical Data and On-Line Mapping
How is data collected? Return to Top How can I view statistical data? Return to Top
Most Census Bureau data are available through the Census Bureau's Internet homepage. However, the public can also access data in other media through local and state organizations that participate in Data Center Programs. Additionally, CD-ROMs are available for purchase through the Census Bureau customer service center. Many other private companies and governmental agencies provide data and various services related to Census Bureau information or products. For more information on these other outlets for data, or how to access and use Census Bureau data visit "How to Access and Use Census Bureau Data" or contact the Census Bureau Customer Service.
Return to Top When will data from the 2000 Census be available? December 1, 2000 – Apportionment Data April 1, 2001 – Redistricting Data Five additional categories of products will be released on a flow basis from June 2001 through September 2003:
So that others may use TIGER database in a geographic information system (GIS) or for other geographic applications, the Census Bureau releases periodic extracts of this database to the public. These extracts are known as the TIGER/Line files. The most recent version is TIGER/Line 2000, available on-line through the TIGER Mapping Services website. TIGER/Line 1999 was released in the summer of 2000 and includes features such as results from the 1999 boundary and annexation survey, updates from census address listings, and major realignment and assignment of address ranges. In early 2001, the TIGER/Line 2000 files came out and included results of the 2000 boundary and annexation survey, Census 2000 tabulation area identifiers and boundaries (available for the first time to the public) and results of more TIGER update operations.
Extract files were created from the TIGER database. These files are digital descriptions of geographic entities that include information such as location in latitude and longitude, name of the object, type of feature, address ranges for most streets, geographic relationships between features and other related information. Since the files are not graphic images of maps, one must have a GIS or mapping software that is capable of importing TIGER/Line extracts.
In addition to TIGER products, you can find related items such as, on-line mapping, cartographic resources and geographic resources at the TIGER homepage.
To efficiently collect the statistical data for the census, the country is divided into a nested hierarchy of geographic entities, of which the counties are the primary components for organizing the census data collection. Below the counties are the census tracts, then the block groups and finally the blocks (which do not always correspond to the city block). These geographic entities were added digitally to the TIGER database. The Bureau also tagged all the features with the geographic codes needed to identify the areas for which it collects and tabulates data (essentially all administrative and statistical area boundaries).
In 1997, the Census Bureau developed the American FactFinder. The American FactFinder provides information about population, housing, industry, business and community profiles. It contains data from the 1990 census, 1997 economic census and other on-going surveys. You can create thematic and reference maps on-line with variables that you specify. No special software is needed to obtain this data and it cannot be imported into desktop GIS. A similar, useful site is the Demographic Data Viewer, which is able to create a thematic map up to the county level.
For purposes of reapportioning seats in the U.S. House of Representatives, state population counts are to be delivered to the President by December 1, 2000.
The Census Bureau will provide states with race and ethnic data to be used for the redistricting process by April 1, 2001.
• Profiles
• Printed Reports
• Electronic Files
• Quick Tables and Geographic Summary Tables
• Microdata Files
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