The Washburn A Mill was built in 1874 and was called the largest flour mill in the world. On May 2, 1878, airborne flour dust ignited. The explosion killed 14 workers instantly and four more died in the fire. Five other mills were destroyed.
Afterward, mills across the country added ventilation and other safety devices. William de la Barre designed a new Washburn A Mill, which opened in 1880 as the world's largest flour mill until 1881.
A fire in 1991 nearly destroyed the old mill. The Minnesota Historical Society opened the Mill City Museum in 2003, with a Flour Tower freight-elevator exhibit that feels like a working mill.