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