Flying distance from Colorado about 600 NM.
From the Visit Dillon Montana website at https://southwestmt.com/communities/dillon.htm
Dillon, Montana has served as a hub for activity in the extreme southwest of Southwestern Montana for at least two centuries. In 1805, the Lewis and Clark Expedition met a band of Shoshone from whom they purchased horses to cross the continental divide. They cached their supplies at Camp Fortunate, just outside of Dillon. As early as 1869 settlers had brought sheep into the area around Dillon , establishing the region as an agricultural center. In 1881 the Utah and Northern Railroad reached Dillon, and Dillon became the point of distribution for supplies from Utah into the gold fields of Montana.
Today, Dillon's reputation as a hub for activity lives on. Several major highways, including Interstate 15, meet in Dillon, making the town a logical epicenter for visitors' explorations of Southwest Montana. In addition, the Beaverhead, Big Hole, and Ruby Rivers all drain into the sweeping valley around Dillon. These destination trout streams alone make the trip to Dillon worthwhile. The adventurous can also travel to the nearby Crystal Park for a day of rockhounding-searching for crystal quartz-in this unique recreation area.