There are miles of old mine tunnels under Grand Rapids

Here’s something most people in West Michigan don’t know they’re driving over: roughly six miles of old mine tunnels run beneath the southwest side of Grand Rapids, Wyoming, and Grandville — about 85 to 100 feet underground. They were dug for gypsum, the soft white rock used to make plaster and drywall. Gypsum was actually Grand Rapids’ very first industry. It was spotted near a local creek back in 1827 and confirmed by Michigan’s first state geologist in 1838, and the mining that followed gave the area some of its names — including Plaster Creek and the nearby village of Paris (as in “plaster of Paris”). Miners blasted out rooms and left thick stone pillars standing to hold up the roof. The tunnels stay a steady 50°F all year, so people found clever uses for them: while the mines were still running, workers grew mushrooms in the dark; after the mining stopped, the cool, dry tunnels became underground storage — for food, and even for stacks of important records (a company still keeps a big share of Michigan counties’ legal documents down there). The last Grand Rapids gypsum mine closed in 1998, once cheaper man-made gypsum came along. One catch of all that digging: in the 1990s, part of the US-131 freeway started to sink because of the hollowed-out ground beneath it, and the state had to build a new route around the unstable spot.