There's a saying that presidents age twice as fast while in office. With Thursday marking President Barack Obama's 55th birthday, take a look back over the past 60 years of U.S. presidents and judge for yourself how much the office aged them.
Now, take a look at President Reagan with Vice President George H.W. Bush during the summer of 1984 at the Republican National Convention during their re-election campaign. Reagan was 73 years old in this photo.