Museum of the High Plains; McCook, Nebraska
This museum was more a collection old junk donated/salvaged by locals rather than an actual museum, but there was some interesting stuff.
Spoiler:
This salt mine actually was quite interesting, the company converted a dormant portion of the still-active salt mine into a museum and tourist attraction. The dormant portions of the mine also serve as a long-term storage facility that is well protected from the elements on the surface. An original IBM System/38 5381 console was down there in the storage exhibit, with what seemed like a beam spring keyboard (I didn't touch it to test). The movie industry also extensively uses this storage facility, as you will see in some of the photos.
Spoiler:

