- Cal-Atlas Geospatial Clearinghouse download center
- California Geoportal
The State of California's portal for geospatial data resources.
- GADM database of Global Administrative Areas
GADM is a spatial database of the location of the world's administrative areas (or administrative boundaries) for use in GIS and similar software. Administrative areas in this database are countries and lower level subdivisions. GADM describes where these administrative areas are (the "spatial features"), and for each area it provides some attributes, such as the name and variant names.
- ICE UC Davis - Information Center for the Environment
ICE specializes in the development and dissemination of geospatial data and technologies; the development of robust data architectures dedicated to the cataloging of global environmental information; and the creation of decision support systems geared toward improving the capabilities of resource managers in a variety of sectors.
- LandScan Global
LandScan is a global population database that shows geographical distribution of population at one-kilometer resolution over an average 24-hour period. The LandScan algorithm uses spatial data and imagery analysis technologies and the most up-to-date census data within an administrative boundary. These population distribution models are tailored to match the data conditions and geographical nature of each individual country and region. The LandScan Global Population Database is developed at the Department of Energy's Oak Ridge National Laboratory
- National Atlas
The U.S. National Atlas website provides a broad array of electronic maps and services delivered online, replacing the 1970's print National Atlas. Coverage is nationwide. You can download GIS data, create customized maps for printing and viewing, and view and print pre-formatted maps on various topics. Map Layers cover various subjects, including 1980, 1990, and 2000 census boundaries, transportation, political boundaries, environment, biology, and climate. For a full list of layers available for download, go to http://www.nationalatlas.gov/maplayers.html
- NHGIS National Historical Geographic Information System
The National Historical Geographic Information System (NHGIS) is a historical GIS project to create and freely disseminate a database incorporating all available aggregate census information for the United States between 1790 and 2000. The project has created one of the largest collections in the world of statistical census information, much of which was not previously available to the research community because of legacy data formats and differences between metadata formats. In addition, NHGIS has created cartographic boundary files compatible with every census, and over 50 million lines of metadata describing the collection. The statistical and geographic data are disseminated free of charge through a sophisticated online data access system.American FactFinder: How do I find all the Census Tracts in a Place?
- Statewide Database
The Statewide Database (SWDB) is the redistricting database for the state of California. In 2001, these data were used for state legislative and local redistrictings following the 2000 Census as mandated by law. Data collection and processing for the redistricting are ongoing tasks conducted over a ten year period of time, starting with the collection of the census at the beginning of each decade. With each election between redistrictings, updated data sets are available as a free, public resource as soon they are processed. Currently the data are being prepared for the 2011 redistricting.
- The National Map
USGS mapping resources from The National Map include a national map viewer, links to historic and current topo maps.
- United States Congressional District Shapefiles
This site provides digital boundary definitions for every U.S. Congressional District in use between 1789 and 2012.