| Resource | Description | Format | 
|---|---|---|
| IPUMS-USA | High-precision samples of the American population drawn from federal censuses and the American Community Surveys | .ASCII | 
| ICPSR | Census data held by ICPSR | .ASCII | 
| data.census.gov | American Community Survey (ACS) Public Use Microdata Samples (PUMS). See tutorials for accessing microdata. | .csv, .sas | 
| Census ftp site | PUMS from 1996 to 2015 | .csv |