Sep 14, 2017 • By

The tunnels that provided flour power

Its powerful current dropped 70 feet at St. Anthony Falls in what is now Minneapolis, Minnesota. So the Mississippi River attracted big dreams of milling lumber and flour as the city was coming of age in the 1860s.

When Cadwallader Washburn and Charles Pillsbury saw the power of the falls, they decided to build their own flour mills nearby.

Today, the Pillsbury A Mill still stands as an unmistakable reminder of Minneapolis’ milling roots. But the old mill now has a much different purpose, as does a tunnel along the riverbank.


This photo of the primary tunnel below the Pillsbury A Mill, and the photo at the top of this post, are from a 2014 report prepared for the city of Minneapolis: “Pillsbury A Mill Tunnel Historic and Engineering Condition Study.”

In 2013, developer Dominium decided to restore the Pillsbury A Mill and convert it into apartments and work and community spaces for people involved in creating art (the A-Mill Artist Lofts). It’s a LEED (Leadership in Energy and Environmental Design) certified building, with a variety of amenities for its residents.

One of the tunnels that were once so crucial to it also has been brought back to life.

As Dominium planned the renovation, the company was interested in a new type of hydroelectric project, to once again harness the energy of St. Anthony Falls and the Mississippi River, and move water through the tunnel.

The developer is just doing it in a different way, as this video explains.

“We wanted to use the tunnels and preserve them for many years to come, and help us be off the grid for the majority of the year,” says Neal Route, development associate with Dominium. “This is a space that was built before modern-day equipment, so you think of all the workers and the time they put into building this great facility. It’s truly incredible.”

Dominium sought to transform the primary dark and muddy tunnel (24 feet tall and 18 feet wide), and they did it in just three months. Along the way, the crews working on the project discovered other tunnels connected to the main channel, as well as a cave (full of bats).

The historic structure and architecture of the main riverfront tunnel is almost as impressive as the Pillsbury A Mill above it.


Water from the river flows into the tunnel under the A Mill through a massive pipe. It reaches a drop shaft where the water drops 40 feet to power a turbine, to supply around 75 percent of the energy for the A Mill Artist Lofts each year.


The tunnel exit area, under the Pillsbury A Mill.

Like the mill’s apartments, the hydropower project is LEED certified.


Without St. Anthony Falls, there would have not have been any tunnels, built on both sides of the river in the 1800s, to power the mills and help shape the city’s growth and our history.

Today the “Falls of Saint Anthony” look nothing like what Washburn and Pillsbury saw as they envisioned the potential for powering their competing flour mills.

“The flour mills used an elaborate network of canals and tunnels to deliver the waterpower from the falls to nearly 30 mills lining both riverbanks,” says David Stevens, public programs specialist at the Mill City Museum in Minneapolis.


Cadwallader Washburn and Charles Pillsbury.

It was Washburn’s investment of $100,000 into a new flour mill along the downtown Minneapolis riverbank that marked the start of the Washburn Crosby Company, later incorporated as General Mills.

Pillsbury had his eye on the water, too. In the late 1870s, he purchased failing flour mills on the other side of the Mississippi, turned a profit in a year and decided to build the Pillsbury A Mill.


The Pillsbury A Mill and St. Anthony Falls, 1897.

When completed in 1881, it was the world’s largest flour mill.

Underneath, Pillsbury had made sure to build his own tunnels to harness the power of the river, power “to turn the wheels of the Greatest Flour Mills of the World,” as seen in the advertisement below.

In 1884, in “The Northwestern Miller,” F.E. Curtis described two wheels which were powered by water that fell more than fifty feet as the “motive power for the vast bulk of machinery.”


“St. Anthony Falls drew business men to Minneapolis because it was cheap and available water power,” says Stevens. “The falls is the reason why Minneapolis was established and became the flour milling capital of the world from 1880 to 1930,” he says.

Washburn and Pillsbury, and their flour milling legacies, are just two examples of how the falls supplied a substantial natural resource for entrepreneurs in what would be known as the Mill City.


St. Anthony Falls, today, looking toward the Washburn side of the Mississippi River (where the Mill City Museum is today, under the Gold Medal Flour sign).

Washburn’s mill complex has been preserved as the Mill City Museum, which opened in 2003 (the largest Washburn mill on the site was damaged by a fire in 1991, but the walls in the damaged area were saved).

The St. Anthony Falls were the only natural major waterfall on the Upper Mississippi River (which starts in northern Minnesota).

If you visit Minneapolis today, you’ll see that the natural falls now have a series of locks and dams, built in the 1950s and 1960s. The concrete overflow spillway (also called an “apron”) at St. Anthony falls was first built after the natural falls partially collapsed in 1869.

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