Why doesn’t the 5-year ACS in IPUMS contain a variable for Census Tract? I would have expected this variable.
Public use microdata is subject to restrictions designed to maintain confidentiality of respondents. One of these restrictions relates to geographic identification. Specifically, geographic areas that are “too small” are not identifiable in public use microdata, such as the ACS data available on IPUMS USA. For this reason, the census tract is not identifiable in the data. If you are looking for aggregated statistics at the census tract level, I’d suggest looking into IPUMS NHGIS. This project provides access to aggregated tables generated by the Census Bureau, rather than microdata. This being the case, the data in this project is not limited by confidentiality restrictions.