The Wapsipinicon Mill began with the organization of the Independence Mills Co. on March 7, 1867, to buy water power and build a custom and merchants flouring mill, and it began operating as a flouring mill on August 1, 1870, at a total cost of $100,000 for the mill and water privileges. The timber-frame building with brick veneer is six stories high including the basement, 112 feet long, 62 feet wide, and 102 feet high, with more than 100 windows for light and ventilation because dust combustion caused explosions and fire. Water enters through arches at the north end, where metal trash racks keep out debris, and the pressure of the flowing water turns turbine wheels that provide the rotary motion for the mill's main power shaft. In 1909 the Wapsipinicon Mill & Power Company was incorporated, and in the 1930's the mill stopped processing flour and focused on custom grinding for livestock feed. Features around the mill include deep grooves on the west wall made by wagon hubs as farmers pulled close to unload grain, corn, or meal, large tie rods and cast iron star brick ties that helped hold the structure square and secure, brick pavers illustrating early Independence streets, a granite horse hitch moved from the McCready Harness Shop, and a rock puller used with oxen or horses to remove native boulders from fields. The site also includes a prairie flower garden reflecting the mesic prairies that once covered much of Iowa. Flour made from grains and other starchy sources was a vital foodstuff, with wheat flour central to many breads and pastries, graham flour developed by Sylvester Graham in the 1830's, and buckwheat flour produced locally for a café during World War II when a flour shortage led to the last use of the mill's buhr stones after buckwheat was shipped from South Dakota. On April 21, 1975, the Wapsipinicon Mill was placed on the National Register by owners Mr. and Mrs. Oliver Greenley, and on December 27, 1975, the Greenleys deeded it to the Buchanan Co. Historical Society, which has drawn on many public and private funding sources for restoration.