Portal #31 Coal Mine was a facility owned by the U.S. Coal & Coke Company, a subsidiary of U.S. Steel. The company built the community of Lynch, then the world's largest coal camp, as a community for miners of Portal #31. At its height of operations in the 1940s, the mine employed more than 4000 people with the community being a virtual melting pot of people including some 38 different nationalities. Visitors can experience the mine by taking the underground mine tour to get insight into the experience of the miners who at one time worked there. In addition to the underground tour, the site includes a walking tour, a 1920s lamp house, bathhouse, and an on-site museum.