In many districts the prospectors followed gold- bearing gravel to the source of the gold in veins, and lode mining began shortly after placer mining. It wa not, however, until about the middle 1860’s, when the Mother Lode and Grass Valley lodes in California and the Comstock Lode in Nevada became important producers, that lode mines became significant sources of gold. Lode production increased rapidly after the discovery of gold in the Cripple Creek district, Colorado, in 1892. By 1898, production from this district together with the increased placer production in California and the accelerated output of the Homestake mine at Lead, S. Dak., had raised our annual gold production to more than 3 million ounces. Production continued to rise with the discoveries of gold at Tonopah, Nev., in 1903, the placer deposits of Alaska in 1904, and gold at Goldfield, Nev., in 1905. By 1905 gold production for the first time exceeded 4 million ounces, a level maintained until 1917. Because of a shortage of manpower during World War I, production then declined rapidly, falling almost to the 2-million-ounce level by 1920, where it remained until 1934. Many gold mines were reopened during the depression in the early 1930’s. When the price of gold was raised in 1934 from $20.67 to $35 per ounce, production increased rapidly and in 1937 again passed the 4-million-ounce mark. Additional gold was obtained as a byproduct from increased output of base metals in the late 1930’s, and in 1940 gold production reached an alltime high of 4,869,949 ounces. Shortly after the United States entered World War II, the gold mines were closed, and gold production in 1944 and 1945 dropped below the 1-million-ounce mark, the lowest since 1849. Production in 1965 was 1,705,190 ounces.

From 1907 until 1943 byproduct gold, obtained from base-metal ores, formed a small, though significant, fraction of the total production of this country. Only in World War II (1943-45 inclusive), when base-metal production increased and gold mines were closed, did byproduct gold contribute more than 50 percent of our annual domestic pro- duction, and since 1951 it has steadily outranked placer production. Most of the byproduct gold is recovered from porphyry copper ores. Large-scale copper mining at Bingham, Utah, has yielded suffi- cient gold to put this district in second place in an- nual gold production in recent years. The Lead dis- trict, South Dakota, has had the greatest total gold production and was also the largest producer in th€ United States each year from 1946 through 1965.

In an analysis of gold-production trends, the pe- riod 1932-59 is particularly informative because it reflects the most flourishing and the most adverse periods of gold mining in the United States. A long period of desultory activity ended in 1934 when the price of gold was increased from $20.67 to $35 per ounce. Mines were opened that had been closed for decades, and the gold-mining industry experienced an unprecedented interval of prosperity. This was ended in 1942 by the imposition of War Production Board Order L–208 (U.S. Bureau of Mines, 1943, p. 80-84), which resulted in most of the gold mines closing for the duration of World War II. After World War II, the gold-mining industry, plagued by constantly rising costs under a fixed selling price, failed to experience the growth and robust activity enjoyed by most industries. Thus, gold mining has been somewhat paradoxical-it reached its zenith in an economic climate unfavorable to most other industries, and it declined sharply when industrial growth was accelerating.

Of the 508 principal districts, in 1959 about 400 were either dormant or had an annual production of less than 100 ounces. Of the 25 leading districts (listed in fig. 2), 8 are dormant, 5 produce less than 100 ounces annually or have sporadic production, and only 12 of them maintain activity comparable to that of the prewar period.