Seemed like a good idea at the time... probably saved us billions by going the silo route.
The MX system was to be built all over the Southwest United States. It would consist of a number of large circular (or close-looped) railroad tracks. All along the railroad tracks are missile sites, most of which are either fake sites or empty underground silos, and only a few of which contain missiles (intercontinental ballistic missiles, aimed at targets in the Soviet Union). A train keeps moving the missiles from site to site in a manner such that the Russians dont know which sites contain missiles. The system was often referred to as the racetrack system.