Southern California's largest gold rush followed the discovery of rich placer deposits by William F. Holcomb and Ben Choteau on May 4, 1860. Miners rushed to the valley and established boom towns. Belleville, the largest, rivaled San Bernardino in population and almost became the county seat. Violence and hangings were common in this remote valley. Over time, major placer and quartz mining declined although some activity continues today.

Citation from California Office of Historic Preservation