Census
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?
- More Information
Statistical Data and On-Line Mapping:
Spatial data and the TIGER Database:
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.
When will the latest TIGER files be available?
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 2008 TIGER/Line, available on-line through the TIGER Mapping Services website.
More information
In addition to TIGER products, you can find related items such as, on-line mapping, cartographic resources and geographic resources at the TIGER homepage.
Statistical Data and On-Line Mapping
How is data collected?
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).
How can I view statistical data?
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.
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. 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, contact the Census Bureau Customer Service.
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