Census Tree is the largest historical U.S. census database, containing over 700 million record links for individuals living in the United States between 1850 and 1940.
Researchers use it to study social mobility and family change across generations. The October 2025 ScienceDirect article Breakthroughs in historical record linking using genealogy data: The Census Tree project, documents applications, including comparisons of occupational mobility between children of immigrants and those with U.S.-born fathers.
The database has also exposed data quality issues—in one instance, census workers fabricated entire census pages.
For genealogists, a YouTube video explores Census Tree’s applications, though it’s technical and detailed. It’s unclear whether Ancestry and similar platforms already incorporate this technology into their hint algorithms.
No word yet on whether this technique will extend to Canadian or British census records.