(California)
Bale Grist Mill State Historic Park is a California state park located in Napa County between St. Helena and Calistoga. The park is the site of a water-powered grist mill that was built in 1846 is one of only two water-driven mills remaining west of the Mississippi River. (Ref: https://en.wikipedia.org/wiki/Bale_Grist_Mill_State_Historic_Park)