What are the oldest US space launch vehicles, or vehicle stages still in use?

I will definitely give you upvotes for answers suggesting any rocket or stage first launched in 1957-1965 and still in use today (actually launched after 2005).

If nothing is found in that period explain and provide younger candidates.

  • $\begingroup$ geoffc's one is better formulated. $\endgroup$ – horsh May 8 '14 at 15:36
  • $\begingroup$ I have to ask, is this a coincidence and just "one of those days", or does your question stem from some article that you both might have read? :) $\endgroup$ – TildalWave May 8 '14 at 15:38
  • $\begingroup$ We've discussed it in comments of a question: space.stackexchange.com/questions/3652/… $\endgroup$ – horsh May 8 '14 at 15:39
  • $\begingroup$ Ah yes, that explains it! Anyway, please leave this question here as there's still some point in having duplicates - makes it easier to find answers via search. It's not a bad question, just unlucky that you both went for the same one at nearly the same time. ;) Cheers! $\endgroup$ – TildalWave May 8 '14 at 15:40

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