Workers seal barrels of flour inside Washburn A Mill, ca. 1875. Photograph by William H. Jacoby.

Interior of Washburn A Mill, ca. 1875. Photograph by William H. Jacoby.

Workers operate flour-roller mills inside Washburn A Mill, ca. 1875. Photograph by William H. Jacoby.

The ruins of a building near the Washburn A Mill after a flour-dust explosion. Photograph by Jacoby, 1878.

The ruins of Washburn A Mill and other mills after a flour-dust explosion, 1878.

Ruins of Washburn A Mill after explosion, Minneapolis, 1878. Photograph by Jacoby.

Ruins of Pettit, Zenith, and Galaxy Mills after the Washburn A Mill explosion, Minneapolis, 1878. Stereograph by Nowack & Chase.

Ruins of Washburn A Mill and other mills after explosion, Minneapolis, 1878. Photograph by Jacoby.

Ruins of Washburn A Mill after explosion, Minneapolis, 1878. Photograph by Jacoby.

Washburn A Mill, Minneapolis, rebuilt after the 1878 explosion, ca. 1882.