Hollowed Earth
THERE IS A VAST NETWORK of underground office, storage, and logistics facilities in the former limestone mines of the USA. These drive-in artificial caves can extend for more than a mile, and house a subterranean analog of the world above. Inside, millions of square feet have been paved, painted, wired, lighted, and walled into underground blocks of commercial real estate. Thousands of people collectively work in these warrens, managing government archives, manufacturing equipment, storing food and data, among other activities.
These underground spaces were the subject of Hollowed Earth: The World of Underground Business Parks, an exhibition at the CLUI in Los Angeles this winter, where this subterranean world was presented video, photos, and touchscreen maps.
There are a few dozen commercial underground business complexes in the country, mostly in the Midwest, Missouri, and around Kansas City. Thick beds of limestone found in this region were mined by boring horizontally into hillsides, into these dry deposits, above the water table. Miners used the room and pillar technique, leaving empty space punctuated by rows of columns of un-mined rock to hold the ceiling up.
Limestone is one of the most common rocks out there, and is used in all kinds of industries, including for cement, fertilizer, and steel, though mostly these days it’s used as aggregate for construction and road projects. Generally quarried in open pits today, there are dozens of underground limestone mines in the midwest and south, mostly left from the old days, before big earth moving and rock crushing equipment was developed.
The vast hollows left by underground limestone mining began to be redeveloped commercially in the post-war boom of the 1950s. Some sites were marketed for safety and security, in an unstable Cold War climate. Others grew simply due to economics—stable temperatures, ease of construction, and a central national location.
The Kansas City area has the most underground business parks. Around 20 million square feet of the city’s business and industrial space is below ground, in ten large-scale redeveloped limestone mines.
Beyond Kansas City, the rest of Missouri is full of limestone, and riddled with known and unknown underground spaces, including natural limestone caverns formed by dissolution of the soluble rock, and mined spaces where limestone and other material were extracted. Several limestone mines in the Ozarks, and around St. Louis, have been turned into commercial business parks and storage facilities.
Beyond Kansas City and Missouri, underground limestone mining took place in Tennessee, Kentucky, and western Pennsylvania, where it was extracted to a large degree by the local steel industry. It occurred in other states, too, though few of these other mines have been redeveloped in a major way.
The majority of former underground limestone mining space remains undeveloped. Even at places that have been redeveloped, there is usually much more space that remains raw. At the edges of the warehouse districts, the caves continue, dirty and dark. These spaces remain, latent—possible underground business parks of the future. ♦