General Data

National Historic GIS (NHGIS)

Good site for finding GIS-formatted historical US census data. Before downloading data, take a look at the online Social Explorer mapping site to understand what the NHGIS site has.

New England Historic Map Sites

Historic USGS Maps of New England and New York (University of New Hampshire)

Digital copies of older USGS topographic maps, download them and georeference them in ArcGIS or Google Earth.

University of New Hampshire Library – Digital Collections

Includes digital versions of topo maps (above) plus 1878 geological atlas of New Hampshire and 1892 atlas of New Hampsire cities and towns