Mullan Road Centerline

by Kristopher K. Townsend, Robert H. Dunsmore, and Richard S. Buswell

To see the map in fullscreen view, in the map's upper-right corner, click the button.
Key: 1859 Route (Townsend)     1861 Route (Townsend)     1861 Route (Dunsmore)     1861 Route (Buswell)     Alternate Route
For more information, click a route's line.

KML file for Google Earth: mullan-road-centerline-5.kml

This Mullan Road centerline describes the general route of the Mullan Military Road built between 1859 and 1861.  It represents many years of research from several individuals and continues to be adjusted as new research is completed.

Rich Buswell, Bob Dunsmore, and Kris Townsend have contributed the data for this map. Both Buswell and Dunsmore's lines were converted from paper maps to digital coordinates by Kris Townsend using GIS-based mapping software and Google Earth. All three researchers have provided other material on this site—see the links near the bottom of this page.


Whenever possible, this centerline map uses tracks recorded with GPS receivers as the researcher walks or drives on likely traces of the old Mullan Road. When this is not possible, the techniques described below are used to approximate the route. Depending on the information available to the researcher, precision varies from 0 feet to perhaps as much as 2 miles Therefore, be aware that this digital, interactive map enables you to zoom in to a level that is often beyond the line's level of precision.

Mullan's route, as with any road, evolved, presenting the map maker with a moving target. Every improvement altered the route to some degree. Some portions were completely replaced with better routes, cuts were made on sides of hills to move the road out of wet areas and newly established pastures. In other areas, it appears that the only changes to the original tread were made by mechanized grading or the rare car, tractor, or ATV.

Private Property

In many places, the original road crosses private land. This map is not an invitation to trespass. Always be aware of land ownership and respect the rights of the land owner by asking for permission. When in doubt, stay out!


Most trail researchers share a common methodology. Sources are studied before heading into the field. Mullan's reports and letters provide maps and descriptions. Early travelers have written about their experiences. Original Cadastral Survey maps often show and label the route. Material from other researchers such as Raymond Borchers, Coleman, and others is often consulted. This, then, leads the researcher into the field to find traces or clues to where the road may have actually been. This study/field work cycle is repeated many times.

Mapping software is often utilized. Township and range section lines provide a reference for transferring Mullan's route from survey maps to a digital map. This track can then be viewed in Google Earth. Google Earth's satellite imagery often shows old road traces and other clues as to where the route may have been.

Mapping software and Google Earth can provide coordinates of possible traces. When entered into a GPSr unit, that tool helps the researcher locate those features in the field. Whenever this boots-on-the-ground observation finds an old trace, it can be walked (and sometimes driven) so that the GPSr can record the coordinates of the actual trace. Those tracking coordinates are then used to refine the centerline presented here.

Drones have found some use in the field. Their elevated perspective can reveal traces not easily seen in Google Earth or on the ground. Drones can also cover far more ground in far less time than walking. After analyzing the drone videos and photos, the informed researcher can then return to the field to inspect these traces on foot.

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