Mile markers on Colorado roads are generally numbered from south to north and from west to east. For example, mile marker 1 on Interstate 25 (MM 1) is one mile north of the Colorado/New Mexico border. MM 1 on I-70 is one mile east of the Utah/Colorado border (odd numbers are assigned to highways running north and south, as I-25. East and west highways are numbered evenly, as U.S. 40).

     Highways that do not begin at the border start with MM 1 one mile east or north of the highway starting point. For example, I-76 runs from Wadsworth Blvd. in the Denver area 180 miles northeast to Julesburg at the Nebraska border. MM 1 is one mile east of Wadsworth and MM 180 is the last mile marker on I-76.

     Another example is state highway CO 119 in the foothills west of Denver. CO 119 begins in Clear Creek Canyon where U.S. 6 bends to the south and CO 119 continues north. MM 1 on 119 is one mile north of the 6/119 intersection. The final mile marker is at I-25 after CO 119 winds through the foothills and turns east at Nederland.

     Mile markers are also used to determine exit numbers on Interstate highways across Colorado. Interstate exits are numbered by the closest mile marker on that highway. For instance, the I-25 Prospect Street Exit 268 at Fort Collins is approximately 268 miles north of the Colorado-New Mexico border and the closest mile marker is MM 268.

     Mile markers are generally posted on the right side of the highway. The markers help to locate incident sites, for example, where a motorist might be stranded.