There should also be a card about the size and weight of a postcard with a 1 year Nikon USA warranty. Most important, save your original reciept, you will need to send a copy in with any warranty repairs, if needed.
Only the D1/2 series has a Nikon USA sticker inside the battery compartment as the serial # is not region specific. Prosumer D80/D200 etc. have region specific S/N and for the USA have a # starting with 3 as was indicated in earlier posts.