NHGIS (National Historical Geographic Information System)This site provides access to data and GIS files for historic census and business titles. Users must register before accessing data, but there is no charge. The site provides easy-to-read charts of data and boundary file availability. Users can select the date, geography, and variable(s) for desired data. Boundary files for GIS use are available either via the Shape Finder option, or in the last step of the data downloading process. Boundary files are not available for all variables and geographies. Download options include SPSS, SAS, Stata, CSV file, GIS CSV file, and shapefiles.