American FactFinder (AFF) is Census.gov's primary vehicle for disseminating Census data. It allows searching and browsing for all kinds of information on geographic areas from the smallest units (blocks) to the largest (the nation). AFF contains information from the most recent and second-most-recent decennial Censuses, plus recent data from the American Community Survey, the Economic Census, and other surveys.
Here's what the AFF main page looks like:
The remainder of the options are for more complicated searches:
A librarian at Western Illinois University offers this more detailed LibGuide covering AFF. Here is her step-by-step guide to the Guided Search. She also has extensive information about the Advanced Search option as well as various mapping options.
NOTE: the following guides refer to older versions of the system; some features may have changed:
The AFF folks at the Census Bureau want users to find the data they need, and they provide some great tools for doing this. Their Help link at the top of all their pages offers step-by-step instructions, and they also provide a glossary and FAQ.
However, the system has some limitations that might be of importance to some users:
If you have other concerns about the data in AFF or problems with using the system, contact them through the Feedback link at the top of every page. As we see through their much improved interface, they do take users' suggestions seriously!
The American Community Survey (ACS) is an ongoing data gathering project of Census.gov that provides information for communities and states in between the decennial Censuses. Its data can be searched through American FactFinder (see box above) or downloaded from the ACS site. The Survey provides data on topics that are no longer covered by the decennial Census, such as economic status, education, disability status, housing expenses, etc.
Here are some primary tools and portals within the ACS system:
The Survey does not cover the whole country. Over 6000 communities are represented by their annual reports, and that number is nearly doubled for the data taken every 3 years. The number of places jumps up to over 670,000 for the 5-year data, and these statistics include data for smaller areas such as tracts and block groups. [NOTE: beginning with FY 2016 (October, 2015) the 3-year estimates will no longer be reported.]
Here is a screen shot of part of ACS' main page, with the important Guidance for Data Users tab expanded and highlighted. Check out their Tutorial for more information on using this data.
In particular, knowing when to use 1-, 3-, or 5-year estimates is a particularly important, but potentially confusing, question. Here is a handy guide that can help answer it. More detail about the survey, especially emphasizing the differences among its types of estimates, can be found in this American Library Association paper: "Librarian's Guide on How to Use the American Community Survey Multiyear Estimates."
Note that not every single bit of ACS data can be accessed from the main ACS page. For a complete collection of data, you must use the Census Bureau's FTP site. Ask a Librarian for assistance if you have trouble finding the data you need.
The Census Bureau has an entire division whose job is make estimates so that researchers and policy-makers can know how the population is changing in between the decennial censuses. Many of these estimates find their way into American FactFinder. But you might want to check out their main estimates portal, by following the link below. In addition to data, they provide extensive information on methodologies used to arrive at the estimates.
This research project at Brown University provides research reports based on Census, ACS, and other data sources that study changes in American society in the recent past.
Here are links to the main site and to some important services they provide: