Washburn A Mill

Washburn A Mill was one of twenty-six Minneapolis flour mills that lined the Mississippi River below St. Anthony Falls during the city’s industrial heyday. By the early 1900s, its company (Washburn-Crosby) was the leading flour miller in Minnesota. The historic building has had five reincarnations in its more than 150 years: an original mill (1874–1878); a rebuilt second mill (1880–1924); a renovated mill (1924–1965); a warehouse (1965–1990); and a museum operated by the Minnesota Historical Society (2003–present).

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The first mill building was constructed by Cadwallader C. Washburn in 1874 at 701–729 First Street South and Portland Avenue. By 1877, Washburn had teamed up with John Crosby to form the Washburn-Crosby Company, and the partners made the A mill their headquarters. After a disastrous explosion and fire leveled that structure in 1878, they rebuilt.

The second mill was a seven-story rectangular structure with a rock limestone face and an interior reinforced with heavy beam construction. It had a flat roof topped with a one-story, three-bay-wide monitor, segmentally arched windows, and walls that tapered from five feet thick at their base to twenty inches thick at their top. While the 1880 building resembled the original mill from the outside, it benefited from new machinery inside: an automatic all-roller system with a capacity of 560,000 pounds (5,000 cwt). An office building and a seven-story wheat house, both attached to the mill itself, provided space for storage and administration.

The Washburn-Crosby Company adopted three groundbreaking technologies inside its new A mill. The land near Minneapolis produced winter wheat, a variety that was not commonly milled in the United States. This required new kinds of milling. The first problem was how to remove the dark, hard husks from the kernels of wheat. For this, Washburn hired Frenchman Edmund LaCroix to develop the middlings purifier: a machine that used jets of air to remove the husks from the flour.

The second major technological development was the introduction of the gradual reduction process. This process used porcelain, chilled iron, or steel rollers to gradually pulverize the purified middlings and integrate the gluten with the starch. The result of these breakthroughs was the production of a product, Gold Medal Flour, that Washburn-Crosby began advertising as the world’s best baking flour.

The final innovation came compliments of William de la Barre, who introduced and installed the Berhns Millstone Exhaust System. De la Barre’s technology solved the problem of flour dust that had led to the massive explosion that destroyed the first A Mill in 1880. Together, these three technological fixes helped make Washburn-Crosby (and its successor, General Mills), one of the biggest modern food companies in the world.

Over time, the Washburn A complex expanded to include a grain elevator (1905), an eleven-story utility building (1914), and a feed elevator (1928). The radio station WCCO broadcast from the utility building starting in 1924, and the Betty Crocker Test Kitchens operated there between 1924 and 1958.

After another fire gutted the mill in 1928, the interior was rebuilt, although the exterior remained largely unchanged. In the same year, Washburn-Crosby merged with three other companies to form GM, and production continued on the Minneapolis site under the new management. GM used the mill to continue manufacturing Gold Medal Flour while developing such dominant global products as Bisquick (1931), Wheaties (1924), Betty Crocker cake mix (1947), and Cheerios (1941).

Washburn A Mill stopped producing flour in 1965. Although it was added to the National Register of Historic Places in 1971, and made a National Historic Landmark in 1983, the building had few tenants, and people without housing used it for shelter. It functioned as a warehouse until 1991, when yet another fire destroyed much of the interior. Shortly after that, the City of Minneapolis stabilized the remains of the mill, and the Minnesota Historical Society announced plans to turn the ruins into a museum. The completed site, Mill City Museum, opened to the public in 2003.