A year ago Donald Trump defeated Hillary Clinton, and the surprises haven't stopped since.
He promised to be a transformational president, to drain the swamp and shake up the establishment.
And he promised that being president would change him — saying that he could become more "presidential" than anyone except Abraham Lincoln.
NPR asked four historians for their take on how the presidency has changed Trump and how Trump has changed the presidency. Here are their observations on Trump, after 10 months in the Oval Office and a year after his election victory.
H.W Brands, author of biographies of Andrew Jackson, Ulysses S. Grant, Theodore Roosevelt, Franklin Roosevelt, Woodrow Wilson and Ronald Reagan
Brands says that being president hasn't changed Donald Trump at all. And that's a surprise.
"Previous candidates who get elected are almost always sobered by the office and the responsibility they take on," Brands says. "Donald Trump shows no evidence of that. He's the same Trump that he was when he was host of his reality TV show. He's the same Trump that he was when he was a candidate."
That's exactly what Trump's supporters wanted. They wanted the candidate who channeled their grievances against the establishment and the elites to do the same thing as president.
If the presidency hasn't transformed Trump, Brands believes Trump has transformed the presidency. The biggest change is the way Trump's "America First" presidency relates to the rest of the world.
"The president of the United States from the 1940s until 2017 was considered the leader of the free world — probably the most powerful person in the world not simply in terms of America's military might, but in terms of the moral authority of the president," says Brands. "Donald Trump has largely abdicated that. He has spoken of ... abrogating America's obligations, at undermining America's alliances and not really caring when other countries violate the human rights of their own people."
Right now, say Brands, the president of the United States is no longer the leading figure in world affairs.
Douglas Brinkley, author of biographies of Gerald Ford, John F, Kennedy, Jimmy Carter, Ronald Reagan and both Roosevelts
To Brinkley, Trump has transformed the presidency through his use of social media.
By tweeting incessantly he sets the agenda for the media and controls the narrative. Every president complains about their press coverage and rails at "media bias." But no president, says Brinkley, has tried to delegitimize the press the way Donald Trump has.
"Richard Nixon ate up a lot of clock trying to destroy the press. Trump now has a mechanism to do it because he's not beholden in any way, shape, or form to traditional media," Brinkley says, "So by going over them, it gives him an instant kind of power and credibility... every day he wants the lead story to be 'Trump.' Even if it's controversial, it allows him to be the dominant force in American politics."
Barbara Perry, director of the Center for Presidential Studies at the University of Virginia's Miller Center and editor of books on George H. W. Bush and Bill Clinton
Perry says Trump has used his dominance to change the traditional relationship between a president and his party. Trump is a divisive figure within the GOP. He's received more scathing public criticism from prominent members of his own party than any other modern president.
But because Trump has succeeded in remaking the party in his own ethno-nationalist, populist image, he has managed to confine that public criticism to just a handful of Republicans. And all of them share one important characteristic — they are no longer running for office. Perry says Trump and his former political adviser Steve Bannon have created a new party line for the GOP.
"It does appear that they have cowed the party regulars. They've cowed the party traditionalists," Perry says. "We have seen it already with the Jeff Flakes in the party, who are having to step aside and actually step out of politics at least for a while. And if that happens, if people who oppose him leave the party, or leave politics, that will be a success for him."
William Inboden, associate professor at the LBJ School of Public Affairs at the University of Texas and onetime staffer in the George W. Bush White House
Inboden points to several areas where Trump has rejected the traditional role of U.S. president. He hasn't embraced the role of "pastor in chief" who consoles the nation at times of tragedy. Instead of seeing his role as a moral authority — someone who tries to unify the country — Trump has been consistently divisive and partisan, particularly after Hurricane Maria hit Puerto Rico and after the recent terrorist attack in New York City.
He's ignored the traditional boundary between the chief executive and the Justice Department, repeatedly calling on the FBI and the DOJ (agencies that are supposed to be independent when it comes to criminal investigations) to go after his political enemies.
As the "legislator in chief" Trump has also departed from past presidential tradition and subcontracted his agenda to his party leaders in Congress. Perhaps as result of his indifference to the details of policy, says Inboden, Trump has yet to sign into law a single piece of significant legislation.
"We talked to Republicans in Congress and they have two concerns: one, sometimes he's not giving them any directions, " Inboden says. "Other times he's giving them five different directions simultaneously."
Historians have already begun to think about the presidency post-Trump. Inboden wonders how many of the changes Trump has made to the office will outlive his tenure.
"As we look at previous presidents who have weakened the authority of the presidency: Nixon did it through overreach and criminality, Carter weakened the presidency through lack of competence in a number of areas, Bill Clinton weakened the president through some salacious behavior," he says, "But President Trump thus far seems to be weakening the presidency primarily through neglect and indifference to the traditional roles of the presidency. And I do worry that whoever his successor is, in four or eight years, will inherit a diminished office."
Trump himself may not have been changed by his time in the White House, but to these four historians, there's no doubt that he's fulfilled his promise to bring big, disruptive change to Washington, D.C., — at least in the short term.