Words can be tricky. Here's an image; I think you'll see the box with Cincinnati on the side as I described, and the cards very clearly being 2011 production from Erlanger. Weird, weird, weird.
It's hard to definitely say what year they were printed - the N code on all the charts I've seen hasn't been used since 1910! One site even claimed that the USPC stopped using the AoS codes in 2009 - obviously not true, since we're still seeing decks with them.
However, since 2000 the letter part of the code went back to A and has gone up one letter each year since (except "B" was used in 1996 and was left out of the 2000-present cycle). Assuming N didn't get skipped in this cycle as it has been for so long, this year would be "N". As confirmation, I looked at the photos of the newly-released USPC version of the Steam Punk deck from T11, and its AoS has an "N" code on it.
This would lead to the conclusion, barring any non-circumstantial supporting evidence directly from a rep of USPC, that your cards were printed in 2011, but that your box dates back to the Ohio factory. Or they're devious and clever forgeries!
That STILL doesn't explain the box that started this thread - a "Classic" style box with Erlanger and (c) 2011 on it. I'm seriously hoping that the USPC just dropped the lame-looking "Standard" style box and reverted back to the "Classic" model.
EDIT: take note of this, from the cypressfilms.com page on dating playing cards:
"Since there are many dates for each letter, you should look at the tax stamp (if any), design of the ace of Spades, and style of the box (if any!) to determine the correct year for the deck. It is also worth noting that older decks can often be found in newer boxes, and vice versa, presumably because inventory of boxes and decks did not always run out at the same time."
So this isn't an uncommon thing, just the first time it happened since the company relocated to a new factory in another city. Thus, the old box you have doesn't list the same city as the guarantee joker card from that box does.