National Historical Geographic Information System

Data Documentation

Tabular Data Sources

Documentation for the digital sources of NHGIS tabular data:

  • Historical Censuses (1790-1960)
  • Modern Censuses: Core Summary Files (1970-2010)
  • Modern Censuses: Special & Supplemental Reports (1980-1990)
  • County Business Patterns (1970-2003)
  • American Community Survey (2009-2014)

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 Boundary Files

The GIS boundary files are based on the US Census Bureau TIGER/Line files with additional editing and digitization to produce historical boundaries in accordance with  several map sources.

Release Log

Two types of releases are documented: updates to the NHGIS website and updates to the NHGIS data (tabular or boundary data).