Wheat and Milling

A short history of milling in Minneapolis, from Wikipedia:

The St. Anthony Express newspaper predicted in 1855 that, "The time is not distant when Minnesota, with the superiority of her soil and seasons for wheat culture, and her unparalleled water power for manufacturing flour, will export largely of this article. ... our mills will turn out wheat, superior in quality and appearance to any now manufactured in the West." By 1876, eighteen flour mills had been built on the west side of the river below the falls. The first mills used traditional technology of millstones that would pulverize the grain and grind as much flour as possible in one pass. This system worked best for winter wheat, which was sown in the fall and resumed its growth in the spring. However, the harsh winter conditions of the upper Midwest did not lend themselves to the production of winter wheat, since the deep frosts and lack of snow cover killed the crop. Spring wheat, which could be sown in the spring and reaped in the summer, was a more dependable crop. However, conventional milling techniques did not produce a desirable product, since the harder husks of spring wheat kernels fractured between the grindstones. The gluten and starch in the flour could not be mixed completely, either, and the flour would turn rancid. Minneapolis milling companies solved this problem by inventing the middlings purifier, which made it possible to separate the husks from the flour earlier in the milling process. They also developed a gradual-reduction process, where grain was pulverized between a series of rollers made of porcelain, iron, or steel. This process resulted in "patent" flour, which commanded almost double the price of "bakers" or "clear" flour, which it replaced.  The Washburn mill attempted to monopolize these techniques, but Pillsbury and other companies lured employees away from Washburn and were able to duplicate the process.
Although the flour industry grew steadily, one major event caused a disturbance in the production of flour. On May 2, 1878, the Washburn "A" Mill exploded when grain dust ignited. The explosion killed eighteen workers and destroyed one-third of the capacity of the milling district, as well as other nearby businesses and residences. By the end of the year, though, seventeen mills were back in operation, including the rebuilt Washburn "A" Mill and others that had been completely rebuilt. The millers also took the opportunity to rebuild with new technology such as dust collection systems. The largest mill on the east side of the river was the Pillsbury "A" Mill, built in 1880–1881 and designed by local architect LeRoy S. Buffington. The Pillsbury Company wanted a building that was beautiful as well as functional. The seven-story building had stone walls six feet thick at the base tapering to eighteen inches at the top. With improvements and additions over the years, it became the world's largest flour mill.  The Pillsbury "A" Mill is now a National Historic Landmark, along with the Washburn "A" Mill.