Detroit’s 100-Mile Underground Tunnel That Few Have Seen

Many cities across America sit atop a massive network of tunnels. This includes thousands of yards of sewage and water pipes, as well as cities like New York City, with its massive subway system, and Las Vegas, with its massive flood-control tunnels, where thousands of residents live below the city.

Everyone knows Detroit as the Motor City, but there's another secret hiding over one thousand feet beneath the surface. Below Detroit is a massive network of underground tunnels that has been used since 1895. The purpose? Salt.

⬇️INSIDE MICHIGAN'S DEEPEST CAVE⬇️

Detroit Salt Mines

Detroit Salt Mines

Now, as someone born and raised in Michigan, I struggle to understand whether I've completely missed something obvious or if the Detroit Salt Mines are a largely underrated part of Michigan. Either way, the mines are a feat of modern engineering that should be highlighted.

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In the year 1895, rock salt was discovered in the Detroit area. This rock salt formed about 400 million years ago, but it wasn't until 1906 that a company, the Detroit Rock Salt Company, tried to mine it. In 1910, a 1,060-foot shaft was dug under the city, and within 5 years of the mine opening, it was removing 8,000 tons of rock salt a month. 

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Today's mining technique is very similar to what it was in this 1960 video about the mine. They drill holes in the rock salt, place dynamite inside, and can blow over a thousand tons from the face and transport it to the surface. Interestingly, the shafts are so small that workers had to bring most equipment down piece by piece and assemble it in the mines.

The mine served the leather and food processing industries for most of the 1900s until it closed in 1983. It reopened in 1998 to instead focus on mining for road de-icing salt. It now produces only one product from the mine. To date, the mine is approximately 1,500 acres large, has 100 miles of roads,  and produces 1.7 million tons of salt annually as of 2017.

Detroit Salt Co

Tours of the mines used to take place back in the 80s, but since the mines reopened around the turn of the century, citizen access has been largely restricted. Ultimately, the Detroit Salt Mines may be Michigan's biggest secret.

Detroit Salt Co.