Bonanza boomed between 1880and 1888. Silver, copper, lead and zinc were found and 1,500 mining claims came into existence,. Soon 37 building flourished along plank walks lining both sides of Kerber and Copper Creeks. The walks blended into the residential section, which grew up the hills and into the forest.
As the price of silver fell Bonanza lost its importance. By 1890 there were only 100 residents but some of the mines stayed in operation. In 1937 a fire wiped out the town of Bonanza and not many structures were rebuilt.
The remains of the Cocomongo Mill are still visible from Forest Road 862. Ore from the Bonanza Mine and Cocomongo Mine was pulverized, mixed into paste and placed in steam heated containers, Mercury and other compounds were added to the mixture to separate the gold and silver. During the mining and milling, heavy metals would seep into the nearby stream. Recently efforts have been made to restore water quality within the Bonanza Drainage.
Otto Mears participated in the mining boom by constructing at least twelve wagon roads, one of which was the Otto Mears Toll Road. It runs between Shirley and Bonanza. A gate was placed at each end of the road and a fee of 10 cents was paid to travel the road. The road wound its way up through Bonanza, over the hill to Shirley, and on to Poncha pass. A narrow gauge railroad line in Shirley picked up ore.