The Thomas-Frederick Mill was one of two built in the Gallatin Valley during the 1860’s to process locally grown grains and guarantee a reliable supply of flour and meal. Flour from here was freighted regularly to the gold camps of Helena, Bannack, and Virginia City. The mill was often forced to shut down in the winter when the Madison River, its source of power, froze over. In a typical water mill operation, a bucket elevator lifts grain to a crib at the center, a screw-driven conveyor moves it horizontally to the hopper at the right, grain is chuted to grinders, and after it is milled, flour flows to a bin, with power for the automation coming from a rotating wheel in the stream.