Here's a little history on the Mill itself taken from their website:
Beginning in 1880 and for 50 years thereafter, Minneapolis was known as the “Flour Milling Capital of the World” and more informally, as the “Mill City.”
The city grew up around the mills. In 1870, the city’s population was 13,000. Twenty years later, it had grown to nearly 165,000.
Grain came in via rail lines that stretched across the Northern Plains grain belt into the Dakotas and Canada. Trains also carried the milled flour to Duluth and to eastern U.S. destinations both for export and domestic distribution.
After World War I, the milling industry in Minneapolis began to decline. As the industry moved out of Minneapolis, the old mills fell into disuse. The Washburn A Mill closed in 1965 and was nearly destroyed by fire in 1991. Its ruins were incorporated into the Mill City Museum.
At the time the mill was the largest and most technologically advanced mill in the world, featuring new automatic steel rollers instead of traditional millstones. During its heyday, it was said that the mill ground enough flour to make 12 million loaves of bread a day.
Two different types of millstones
A large Bisquick sign
The best part of the museum is the multi-story Flour Tower, in which visitors sit in the cab of a freight elevator and are taken to different floors of the building, each designed to look like a floor in a working flour mill.
Here are a few pictures of the different floors of the building - the pictures didn't turn out the greatest because we weren't allowed to use a flash.
On May 2, 1878, a spark ignited airborne flour dust within the mill, creating an explosion that demolished the Washburn A and killed 14 workers instantly. The ensuing fire resulted in the deaths of four more people, destroyed five other mills, and reduced Minneapolis’s milling capacity by one third. Known as the Great Mill Disaster, the explosion made national news and served as a focal point that led to reforms in the milling industry. In order to prevent the buildup of combustible flour dust, ventilation systems and other precautionary devices were installed in mills throughout the country. (Wikipedia)
These are the only pieces of equipment that survived the fires.
Here are some replicas of the type of equipment that was used in the mill in the 1880s.
This is a middlings purifier used to remove the husks from the kernels of wheat.