With so many hours spent in the Oval Office, it's no surprise that presidents have been known to put on a few (or many) wrinkles during their time in the White House.
While some leaders have aged gracefully ... others have not -- and for good reason!
Barack Obama's transformation will make your jaw drop and the same goes for Ronald Reagan. And we gotta say, Jimmy Carter fared well in the aging department.
Take a look at the slideshow above to see how U.S. presidents have aged during their time in office.
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