Maps and GIS
Library Catalog -- All the maps held by the Library can be found here
U.S. Geological Survey (USGS) Publications Warehouse -- Portal to all publications of USGS
Geographic Names Information Service (GNIS) -- Lexicon to all the places in the world as well as links to digitized maps and aerial photographs
The National Map -- The offical map of the United States includes various data layers
Colorado Office Information Technology, Geographic Information Systems -- Links to Colorado GIS data
National Map, Seamless Server -- Download U.S. and world GIS data