[I submitted this article to Damn Interesting in hopes of becoming a periodic writer for them.]
Three hundred and fifty million years ago, the vast area between the Rocky Mountains and the Appalachians was covered by what we now call the Colorado Sea. The sea is thought to have extended from Mexico all the way up into the Arctic during the Cretaceous Period. Over millions of years, the accumulation of calcium, magnesium, and other minerals on the ocean floor formed deposits of limestone, shale, and chalk so enormous that today, in some cases, they are the size of entire states. In fact, limestone is mined in 92 of Missouri’s 114 counties, and Kansas is home to one of the world’s largest chalk mines.
Limestone is used in everything from pharmaceuticals (antacids, like Tums, are almost 100% powdered limestone) to the building of roads. Farmers use limestone to neutralize the acidity of their soil, and limestone has extensive use today as a raw material in Portland Cement. Limestone is everywhere and it is used in everything. And we have the ancient Colorado Sea and millions of years of compression to thank for its plentifulness. In Missouri alone, 75 million tons of limestone products are produced each year — that’s about 10 tons for every resident!
In the late 1800s, mining of limestone began in the Kansas City, Missouri area. At that time it was primarily quarried, however, by the 1950s, leaving usable subterranean space started to become an aim of miners. They used something known as the “room and pillar” method of hard rock mining which left a grid of twenty-five foot square limestone columns to support the weight of the “roof.” In between these pillars are tunnels, some of which are sixteen feet high and forty feet wide.
One particular mine called Bethany Falls was purchased by the late owner of the Kansas City Chiefs football team, Lamar Hunt. His development company, Hunt Midwest Real Estate, has turned this mine into the World’s Largest Underground Business Complex™. Called SubTropolis, this massive complex is 160 feet beneath the surface, contains roughly seven miles of illuminated and paved roads (along with miles of railroad tracks), and currently has five million square feet of occupied office and warehouse space, with millions more still being developed.
One of the largest tenants is the US Postal Service which uses the large and climate controlled space for the storage of stamps for collectors. The space also houses thousands of Hollywood’s classic movie reels, including the original “Gone With the Wind.” Many other spaces are filled with libraries, computer labs, and other commercial office space, and it is even home to the nation’s only sanctioned underground 5K and 10K races, the KC Groundhog Run. Everyday more than 1500 employees report for work at the bottom of the Colorado Sea for over fifty different businesses located in the SubTropolis complex, where the weather is always 70 degrees and overcast.