I know this thread is ancient, but another "only in the USA" item is seeing the Amish, preferably in Pennsylvania Dutch country, and eating at a down home Amish or Mennonite run restaurant.
Actually, my favorite is in Grantsville, Maryland -
The Penn Alps. Friday nights are especially yummy (try the dried corn!), but even you don't eat, the Artisan Village is amazing! I've yet to leave without buying
something!
ETA: And for heaven's sake, please be respectful, and don't try to take their pictures! It's terribly rude, and there are plenty of postcards you can buy instead. Even their dolls don't have facial features.
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