The Washburn A Mill Explosion of 1878

The Washburn A Mill was a flour mill in Minneapolis, Minnesota. Built in 1874 under the direction of the excellently-named Cadwallader C. Washburn, it was frequently touted as being the world’s largest flour mill, though the claim may or may not be true. No one officially kept track of that kind of thing back then, as people generally had better things to do.

The facility was almost completely destroyed by an explosion in the spring of 1878.

Early Minneapolis Landmark Goes BOOM!

Washburn A Mill’s flour grinding equipment was powered by the flow of water down St. Anthony Falls on the Mississippi River, located in what is now the heart of Minneapolis. The mill’s incredible milling capacity—it was also claimed that the mill could grind more than 100 train boxcars’ worth of wheat into roughly 2 million pounds of flour every day—contributed to Minneapolis’ significant growth during the late 19th century.

Photo credit: Internet Archive Book Images via / No known copyright restrictions

Photo credit: Internet Archive Book Images via / No known copyright restrictions

On 2 May 1878, a spark of unknown origin ignited the dense flour dust within the mill, causing a massive explosion and ensuing fire. The mill itself was all but leveled in the explosion; at least eighteen mill workers were killed instantly. The fire raged out of control and destroyed five neighboring mills. The Great Mill Disaster, as it came to be known, reduced Minneapolis’ considerable milling capacity by a third.

As was the norm at the time, Washburn A Mill had no interior ventilation system in place to minimize dust explosion risk. The phenomenon was not unknown at the time, as similar accidents had occurred at other, smaller mills around the world. However, the destruction of such a large and well-known facility became a major national news story, and ultimately led to numerous safety reforms in the milling industry.

After the Tragedy

A new (and improved) Washburn A Mill was built on the site and completed in 1880. Designed by Austrian engineer William de la Barre, the new mill was, once again, said to be the largest in the world—advertisements boasted: “This is the largest and most complete mill in the United States, and has not its equal in quantity and quality of machinery for making high and uniform grades of Family Flour in this country.”

The new mill put Minneapolis’ milling industry back on track, and helped the city continue its growth into the new century. Washburn (the guy, not the mill) joined forces with John Crosby soon after, forming what is now General Mills. The mill was finally shuttered in 1965, after decades of reduced production and General Mills’ increased emphasis on cereals and baking mixes rather than straight flour.

The Washburn A Mill site today. Photo credit: amee@work via / CC BY-NC-ND

The Washburn A Mill site today.
Photo credit: amee@work via / CC BY-NC-ND

The disused Washburn A Mill was nearly destroyed by fire in 1991. Soon after, however, the Minneapolis Community Development Agency announced plans to stabilize the ruins, partially rebuild the mill, and turn it into what is now the Mill City Museum.