From the mid-1850s to the early 1900s, this was the site of an active coal mining town. Somersville was one of five towns that existed during the mining boom of the Mt. Diablo Coal Field. At the peak of operation, it is believed that Somersville and nearby Nortonville were the largest communities in Contra Costa County. Approximately 900 people were supported by Somersville's five coal mines: the Pittsburg, Union, Independent, Manhattan, and Eureka.
Coal was carried by rail from the mines to Pittsburg Landing on the San Joaquin River, and from there by riverboat to markets in San Francisco, Stockton, and Sacramento.
By the late 1800s, mines began to close due to increased production costs and competition from higher quality Washington Territory coal. The town of Somersville slowly died.
Mine waste rock piles, exotic trees planted by residents, and Rose Hill Cemetery are all that remain.