Out of service but not necessarily abandoned. The F series silos in some instances were reused as machine shops, I understand.
They have first rate climate control systems in them. The Atlas missiles were basically giant aluminum bags that were kept inflated when they weren't fuelled. An Atlas missile with no fuel in it would essentially crumple to the ground; without the fuel load there was nearly zero structural strength. There's an F model in Huntsville, AL at the space and rocket museum. As old as it is; it's still being inflated by a constant nitrogen tap. You can see the generator and tanks sitting behind the missile, which is lying on an extremely rare transport trailer.