- Las Animas County, Colorado's most extensive county, is more than 4.56 times the size of Rhode Island, 2.44 times the size of Delaware, and 98% the size of Connecticut.
- The Colorado Organic Act of 1861 defined Colorado as an ellipsoidal rectangle bound by the parallels 37°N and 41°N latitude and the meridians 25°W and 32°W longitude from the Washington Meridian.
- 160 years of subsequent government land surveys redefined the state boundaries as a ellipsoidal polygon of 697 sides.
- The southwestern corner monument of the Territory of Colorado later became the common boundary point of the U.S. states of Colorado, New Mexico, Arizona, and Utah known as the Four Corners.
- Colorado, Wyoming, and Utah are the only three U.S. states with no natural boundaries.
- Although Colorado and Wyoming have the same shape and both measure four degrees of latitude by seven degrees of longitude, Colorado is 6.42% more extensive than Wyoming because it lies closer to the equator.
- Gilpin County and Clear Creek County are the only two Colorado counties to retain their original 1861 boundaries.
- All 21 of the highest U.S. counties by mean elevation are in Colorado.
- Jefferson County borders ten other Colorado counties.
- The City and County of Denver and Delta County each border only three other Colorado counties.
- Twelve Colorado counties have the same name as their county seat.
- Nine Colorado counties have no incorporated municipalities other than their county seat.