This set of guides gives some general information on finding Census data online, primarily on the Census Bureau web site. For more detailed instruction and tutorials, consult the sources under the Other Guides to Census Information tab.
For information on the Library's holdings in tangible form (print, microfiche, CD/DVD) see our LibGuide Census Information in the Library.
Data at Census.gov is available in a variety of formats. Much basic information is provided on normal web pages, through drop-down menus and other devices (for some data to display, Java must be enabled). More extensive files might be available for download in spreadsheet or PDF format. Electronic versions of publications such as documentation and historical reports are usually in PDF format.
As required by the Constitution, the Census Bureau conducts a complete count of residents of the U.S. every ten years. Simple counts of people in states and areas must be available by the beginning of the year following the Census because this data is used to apportion Congressional seats. The other data (income, education, etc.) generated by the Census surveys usually takes a few years to become available. This detailed data, giving social and economic characteristics of the population of small geographical areas, is usually not available until at least three years after the Census was taken.
The more detailed the statistics one searches for, the less detailed are the geographical areas for which the statistics are available. For example, in past Censuses, general population counts were published for places as small as 1,000 people. But poverty status figures were given only for places as small as 2,500. Detailed cross-tabulations of poverty status and educational level may only be given for large (more than 250,000) cities. Thus, two parameters are important when selecting a Census report to study: the kind of statistics one needs, and the geographical area of interest. For more information on Census geography, see the Geography page.
Information contained in the Census volumes is collected from questionnaire responses. Some basic information (e.g.: age, sex, race) is obtained from all residents, whereas other, more detailed questions (e.g.: income, education, employment status) are only asked of a sample. And some questions are not asked at all, (for example, "what is your religion?") which means that no data on these subjects is available from the Census Bureau. For more information on the importance of Census methodology, see the Comparability page.
The State Data Center system is a partnership between the Census Bureau and the various states and US territories. Back in the days before the internet, these centers provided a closer-than-Washington source for printed reports and data. Now they continue to provide somewhat localized contacts for data of particular interest to their states and regions. Plus, some states' centers have taken on larger projects and provided interesting and useful applications, portals, and other resources to the country as a whole.
Look for links to these Centers by following the navigation link on the left.
Finding data on the Census Bureau website requires navigating through a lot of jargon. These three acronyms are a basic starting place for learning what you need know:
American FactFinder has a lot of flexibility built into it (see this Guide) but if you need more, try another Census Bureau tool: Data Ferrett. With it, you can mix data from different tables and different datasets to make your own customized tables (data is also downloadable).
From the tables you can easily create graphs and maps. For even more sophisticated users and content developers, they offer an Application Programming Interface (API) as well.