Tabular Data Sources
Documentation for the digital sources of NHGIS tabular data:
- Secondary Sources (1790-2010)
- Decennial Census Summary Files (1960-2020)
- County Business Patterns (1970-2003)
- American Community Survey (2009-2024)
Time Series Tables
Time series tables link together comparable statistics from multiple censuses. The documentation describes how time series are constructed; summarizes which topics, years, and areas are covered; and provides a listing of all table sources and notes.
GIS Files
The GIS files are mainly based on the U.S. Census Bureau TIGER/Line files with additional editing and digitization to produce historical boundaries in accordance with several map sources.
Revision History
The Revision History documents all significant updates to the NHGIS website and to NHGIS data (tabular or boundary data).