Apparently (going on my memory here so please bear with me) there was some sort of invasion plan cooked up by Hitler and the Japanese. They had a plan to divide the occupation of the US at the Rocky Mountains..everyething west of the Rockies would be administered by the Japanese, everything east would be run by the Germans.
Of course, in the mid-50's the memory of the war was still recent, so there were still articles focussing on how dangerous Hitler was, and perhaps this was a fantasy or an exagerration. However, as a child, let me tell you that the map they showed left a HUGE impression on me, if I could remember it all these years later.