Just ten days ago, at Jimmy Carter's state funeral at Washington National Cathedral today, all five living U.S. presidents attended: Bill Clinton, George W. Bush, Barack Obama, Donald Trump, and Joe Biden. Today, all five men were once again in the same place, as Clinton, Bush, Obama, and Biden attended Trump's inauguration.

Michelle Obama was the only spouse absent from the service last week at Washington National Cathedral, where her husband and Trump were seated next to each other and chatted and laughed like old friends despite the history of political animosity between the Democratic former president and the returning Republican.

Former President George W. Bush was spotted at the inauguration of Donald Trump. See pictures of the former president here.

Presidential scholars say it's not worth it for Bush to get involved in public spats with Trump and say it will only hurt him in the history books.

Carter struck a balance between satisfying the needs of employers and protecting American workers from foreign labor competition. That tension has never let up.