The Family History Library has a small collection of maps for Colorado and early western territories, including a set of topographical maps for the state. The library also has city ward maps of Denver for the year 1874 (Family History Library film 1377700; fiche 6016642). A series of maps showing changes of county boundaries between 1861 and 1913 is in Colorado Maps (n.p.; Family History Library book 978.8 E7cm).
The largest collection of maps in Colorado is in the map library of the University of Colorado at Boulder. A specialized map collection for Colorado and the southern Rocky Mountain area is in Fountain Valley School's Science Department at Colorado Springs. The Denver Public Libraryand the Colorado Historical Societyalso collect maps and atlases. The Colorado Division of State Archives and Public Recordshas the incorporation filings and original plats for most towns.
United States Census Bureau State and County Map. This map will allow you to zoom in on any state or county in the United States and read the names of all of the neighboring counties.
Base Map of Colorado (Univ of Texas) - Nice basic map showing Counties of Colorado
Clickabe Map of Counties of Colorado - Takes you to county government sites.
Maps of Colorado - University of Texas
Map Library - University of Colorado at Boulder
Historical Maps of Colorado - University of Alabama Map Library
Historical Maps - Open Directory Project
National Atlas of the United States - Printable maps of the United States
Maps of Counties of Colorado - Digital-Topo-Maps.com. Various county maps can be purchased.