Really? I guess it still is "One Nation" technically. I even remember when we really were one nation, united. I also remember hearing and seeing the B-36's flying over my Grandparent's house and the steam driven coal fired trains when the diesels were new. We are very much less a single nation today than we were post WWII / pre-Korean Conflict. I guess that an existential, external national threat causes that attitude.
we may still be one nation, but we have weakened all 57 states.