Principal Gold Producing Districts of the United States
Arizona ranks eighth among the gold-producing States; a total of about 13,321,000 ounces of gold was mined from 1860 through 1965. Deposits of copper and silver were known long before the Territory was acquired by the United States, but hostile Indians and lack of water discouraged any large-scale prospecting or mining. In the 1870's, after the transcontinental railroads were completed and the Indians ceased hostilities, Arizona's gold deposits received considerable attention. Mining activity increased considerably in the early 1900's, when the large porphyry copper deposits at Ajo, Bisbee, Globe-Miami, Clifton-Morenci, Ray, San Manuel, and Superior were developed. Large-scale mining of these and other copper deposits continues, and most of the gold produced after 1900 has been a byproduct of these ores.
Colorado ranks second among the gold-producing States; its gold output through 1965 was about 40,776,000 ounces. The first publicized discovery of gold in Colorado was in 1858. The immediate rush to the Denver area resulted in important placer finds near Idaho Springs and Central City. Prospectors ranging far up the Arkansas River valley found gold placers near Leadville as early as 1859. Many rich gold lodes were quickly discovered, and Colorado soon became a major mining area. In the 1870's, important ore discoveries were made in the San Juan Mountains, the Sawatch Mountains, and in the Leadville-Breckenridge area. Gold ore was found in the important Cripple Creek district in 1891.
Idaho, which ranks ninth among the gold-producing States, is credited with producing 8,323,000 ounces of gold from 1863 through 1965. The earliest recorded discovery in Idaho was of placer gold along the Pend Oreille River in 1852. Rich placers were found soon afterward at Pierce City, Elk City, Orofino, Boise Basin, Florence, and Warren, and a brief period of feverish activity followed. By 1870, many of the richer placers were exhausted, and an intensive search for lode deposits resulted. Large-scale dredging rejuvenated the placers, though after 1900, most of Idaho's gold was produced from lode mines.