The IPUMS National Historical Geographic Information System (www.nhgis.org) provides free online access to summary tables and GIS files for U.S. censuses and surveys going back to 1790. NHGIS also provides time series tables, which link together comparable statistics from multiple censuses. Our “geographically standardized” tables provide 1990, 2000, and 2010 statistics for 2010 census units at 10 geographic levels, including census tracts, block groups, and ZIP Code Tabulation Areas. These tables use advanced interpolation methods to produce high-quality estimates where boundaries changed between censuses. This webinar provides an overview of current and planned NHGIS time series features, describing our interpolation methodology, demonstrating advantages of our approach, and previewing our plans to extend tables to cover more years and subjects.