San Juan County is in the western San Juan Mountains in southwestern Colorado, just south of Ouray County.
The county produced about 1,665,000 ounces of gold through 1959 and large quantities of silver, lead, copper, and zinc. The bulk of the gold came from lodes in the Animas (Silverton) and Eureka districts. There are no extensive placer deposits in the county.
Some prospecting in the county was carried on in the 1860's, and the first gold ore was mined in 1870 while the region was still part of the Ute Indian Reservation. The main rush to the region did not begin until 1874, after a treaty with the Ute Indians opened the region to settlement (Ransome, 1901b, p. 19-20). About 2,000 men came into the district during the summer of 1874, and at least that many claims were staked. San Juan County was formed in 1876 with the county seat at Silverton.