Exchange

See the 'U.S. Returns & Refunds Policy' section in:

Returns & Refunds - Shopping Help - Apple

You can always return the item to any U.S. Apple Store. An Apple Specialist will assist you with your return. Your refund will be processed at that time. To locate an Apple Store in your area, please refer to the Apple Retail Store Locator.

If you purchased your item from Apple in the U.S., you can take it to any U.S. Apple Store for an exchange. Item exchanges are, of course, subject to in-store product availability. It's a good idea to check if a product is in stock by visiting apple.com and then seeing if it's available for pickup at a store nearby.

Just to make sure, if you made this purchase from another retailer than Apple, you would have to check their return policies. Just want to make sure all bases are covered.