The Madison Limestone is a thick sequence of mostly carbonate rocks of Mississippian age in the Rocky Mountain and Great Plains areas of the western United States. The rocks serve as an important aquifer as well as an oil reservoir in places. The Madison and its equivalent strata extend from the Black Hills of western South Dakota to western Montana and eastern Idaho, and from the Canada–United States border to western Colorado and the Grand Canyon of Arizona.

Lewis and Clark Caverns State Park is a 3,000-acre (1,200 ha) public recreation and nature preservation area located twelve miles (19 km) east of Whitehall in Jefferson County, Montana. The state park includes two visitor centers, ten miles of hiking trails, a campground, and its namesake limestone caverns. The Lewis and Clark Caverns Historic District was placed on the National Register of Historic Places in 2018.