It dates back to the Cold War era in the late fifties…a group of Kansas businessmen were seeing a need in the business community to store sensitive and vital records and information underground. It was the height of the Soviet Union and United States' tension in the Cold War. Nuclear warfare was top of mind for everybody, and to get everything that was important underground was a key driving element of the security of the day, and it was that need to find a location that led that group to Hutchinson, to the salt mine. Here we're in a salt mine that has been in operation since the twenties. And space was not a limiting factor--there was plenty of room, controlled access in and out, and a perfect storage environment, so it just kinda came to be that it was the ideal spot.
No water, no insects or animals, constant temperature and humidity, and that's why so many Hollywood films, videotapes, props, and other memorabilia are stored there -plus governmental archives the company won't tell us about. Link -Thanks, John!