8. The Pillsbury A mill in Minneapolis is a National Historic Landmark in Minneapolis
When it was opened in 1881 after more than a year of construction and half a decade of planning which preceded it, the Pillsbury A mill was the largest in the world in terms of milling capacity. Typical mills of the day were capable of producing about 500 barrels per day. The Pillsbury mill was designed to produce 5,000 barrels per day, though it did not run at full capacity for many years after its opening. It was the first of many mills which were designed to operate at what had been unheard of levels, and because of the vibration of the milling machinery the walls of the building required reinforcement over the years. Nonetheless the walls bow inward at the top of the building, with a deviation of more than twenty inches. The stone walls of the building are load bearing, and after the walls were completed they were reinforced with wooden timbers on the inside of the building.
Each of the building’s seven floors and its basement had a unique function which contributed to the mill’s operation. The mill was driven by a pair of waterwheels which were in turn driven by the Mississippi River along which it was built. Combined the waterwheels provided 2,400 horsepower to drive the machinery of the mill. Pillsbury operated the mill for its intended purpose until 2003, when it closed the facility. By then Pillsbury had been bought by Diageo, and it was later sold to General Mills. The giant mill building was acquired by local developers and converted to use as lofts in the early twenty-first century. The waterwheels were replaced with hydro-electric turbines which generate three quarters of the building’s electrical requirements.