About the Data
Free Data Downloads
The data on this web site are available in several commonly-used formats:
- As dynamic web-based maps. A web browser that supports Dynamic
Internet Explorer® or Mozilla
Firefox® supports this capability.
Because of inconsistencies between their implementation of Dynamic HTML,
this site has been optimized for Internet Explorer. Maps are organized
by district types: state house, state senate and U.S. congress. They
should be viewed with a computer screen set to at least 800x600 resolution
and 65,000 colors.
- As Microsoft
Excel® spreadsheets with an
.xls file extension.
- As ZIP files, which need to be
unzipped into their original formats before they become accessible
by software such as word processors, GIS software, databases or spreadsheets.
Zip files are files that have been compressed for faster download.
For example, congressional district boundaries and data may be available
in the following zipped shapefile: C0926shp.zip. The "shp" string in
the name arbitrarily denotes a shapefile while the ".zip" extension
indicates that this shapefile was compressed for faster web download.
To use this file with a GIS system such as ArcView, the file must first
be unzipped. Unzipping it will create a set of new files on disk, which
can be read by the GIS. There are a number of unzipping utilities available.
The most popular of them is WinZip. A free trial version of WinZip can
be downloaded from here.