POLK COUNTY MILL & LBR CO.
Black Rock
May 21, 1907: "The Polk County Mill & Lumber Company, of Black Rock, are cutting about 30,000 feet every day. The timber at this mill is fine, soft yellow fir, and is being converted into ties and railroad timber. This concern also cuts alder and maple. The company has recently installed a Washington Iron Works engine in their camp." (Polk County Observer)