Encyclopedias, Almanacs, Transcripts, and Maps
- color index
- Colorado National Monument
- Colorado Plateau
- Colorado potato beetle
- Colorado School of Mines
- Colorado State University
- Colorado–Big Thompson project
- Colosio Murrieta, Luis Donaldo
- colter
- Colter, John
- colugo
- Columbia basin project
- Columbia College
- Columbia Heights
- Columbia Plateau
- Columbia sheep
- Columbian Exposition
- Columbus Day
- Columcille, Saint
- Colwyn Bay