President Obama and former President George W. Bush at the dedication of the George W. Bush library in Dallas. Alex Wong/Getty Images hide caption

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President Obama, former presidents George W. Bush, Bill Clinton, George H.W. Bush and Jimmy Carter attend the opening ceremony of the George W. Bush Presidential Center on Thursday in Dallas, Texas. The Bush library, which is located on the campus of Southern Methodist University, with more than 70 million pages of paper records, 43,000 artifacts, 200 million emails and four million photographs. Alex Wong/Getty Images hide caption

itoggle caption Alex Wong/Getty Images