Argonaut Mine, discovered in 1850, and Kennedy Mine, discovered in 1856, played dramatic roles in California's economic development. Together they produced $105,268,760 in gold. Kennedy Mine had a vertical shaft of 5,912 feet, the deepest in the United States, and changed mining methods in the Mother Lode. Argonaut Mine was the scene of the Mother Lode's most tragic mine disaster, when forty-eight miners were trapped in a fire at the 3,500 foot level on August 27, 1922, and a few survived. Both mines closed in 1942.