21. Historical, Demographic, Economic, and Social Data: The United States, 1790-2002 Bookmark Format Series - completed
25. LIFE-M: The Longitudinal, Intergenerational Family Electronic Micro-Database Bookmark Format Single study
27. National Historical Geographic Information System (NHGIS) via IPUMS Bookmark Format Data archive or collection
29. New Area- and Population-based Geographic Crosswalks for U.S. Counties and Congressional Districts, 1790-2020 Bookmark Format Single study