In the early 1960's, Lamar Hunt of Hunt Midwest began to develop one of the largest underground storage facilities. The company realized that their underground limestone mine created the perfect climate conditions for an underground business complex. It was named Subtropolis. It now has over 50 million square feet of underground space. Companies like Subtropolis have since proliferated throughout Missouri.
An abundance of limestone in Missouri has created a rich mining industry. Over 3 billion tons of limestone have been mined which has left many chasms beneath the surface. Inside these underground spaces, there is a constant temperature of 65 to 70 degrees fahrenheit. Because they are underground they maintain a consistent relative humidity. This makes the underground spaces highly efficient and ideal for storing paper, food, and film. There has been a contemporary interest in repurposing these mines into usable industrial space.