Plymouth Consolidated Mines was founded in 1852 from several claims and consolidated in 1883. It was sold to the Argonaut company in 1925 and closed in 1943. Empire workings reopened in 1946-47. The Pacific shaft was 4450 feet deep. Total production was $13,500,000. Mines to the north as far as the Cosumnes River included Aden, Alpine, Green, and Bay State.