Humans have relied on grains for millennia as a main staple of their diet, and making flour for eating required threshing wheat and grinding corn in grist mills. Threshing removed the edible grains from the ends of cut and dried plant stalks, traditionally by beating them with a flail against a wooden threshing floor inside a barn or shed, after which mills ground the separated grain into flour for consumption or sale. Caleb Crosby designed this threshing barn for his farm in Grainger County in the 1830's, and family and slave labor built it. Oxen or mule power turned this unique barn into a giant machine that threshed the Crosby farm's wheat, reflecting how the Crosby family, like many other American farmers of the time, sought to speed production and get more from the land. The barn remained at its original location on the Crosby farm along the Holston River for another century, but the Tennessee Valley Authority's construction of Cherokee Dam threatened it. In 1940, the Crosby family donated the barn to the Cades Cove project in the Great Smoky Mountains National Park, but because it had not originally stood in Cades Cove, park administrators chose not to rebuild it. After 30 years in storage, National Park Service officials transferred the barn to Norris Dam State Park to join the historic Rice Gristmill, and state officials reassembled it there in 1975.