Discovered in 1880, the Congress Mine was the largest gold mine in Arizona by the turn of the century. Congressʼ prominence was marked in 1901 by a visit from President McKinley, who was a staunch champion of the gold standard. It yielded close to 400,000 ounces of gold between 1891 and 1911. The amount of gold discovered historically through the use of relatively primitive exploration and prospecting techniques was a strong indication of the richness and untapped potential of the mine, according to Malartic Hygrade in 1989. Malartic, a public Canadian gold mining company, which later changed its name to Republic Goldfields, mined the Congress commercially from 1990-1992. In its first year of production Republic Goldfields produced 28,500 ounces of gold and 33,000 ounces of silver. This was based on an average of 343 tons per day processed.