He changed America’s approach to trade. He transformed the nation’s relationship with China. He altered the country’s role in international institutions. He remolded the nation’s alliances. He reshaped American views about immigration. He modified decades-old customs of politics. He weaponized social media.
He recast ancient notions of how leaders behave, speak and relate to one another. He spawned a debate about whether he endangered democratic values, undermined the Constitution and stirred racial tensions.
But most significant of all: He remade two of the three branches of government.
As a result, Donald J. Trump may be pilloried by contemporary scholars even as he is remembered in history as the most consequential president in three-quarters of a century and the most significant one-term president in nearly 175 years.
Not since Franklin Delano Roosevelt has an American president so changed the institution of the presidency — and Mr. Trump served only a third of the time FDR spent in the White House. Not since James K. Polk has a one-term American president done so much to change the profile of the country — and Mr. Trump did it without shepherding even a fraction of the substantial legislation through Congress from 2017 to 2021 that Mr. Polk did between 1845 and 1849.
Mr. Trump was an orange tornado rampaging through American politics, diplomatic relations, global institutions and the volumes of American etiquette from Emily Post to Miss Manners. He repealed George H.W. Bush’s approach of “the outstretched hand” and rescinded Franklin Roosevelt’s dictum that the presidency “is pre-eminently a place of moral leadership.”
But the next sentence in Gov. Roosevelt’s 1932 interview in The New York Times before he defeated Herbert Hoover is less often quoted. He said significant presidents “were leaders of thought at times when certain historic ideas in the life of the nation had to be clarified.”
Historians for years will wrestle over whether Mr. Trump clarified or muddled historic ideas. They will evaluate whether Mr. Trump permanently recast long-established principles in the presidency. They will argue over whether he was a plutocrat, populist — or poseur.
But this debate is not only for the future. It is occurring now.
“Outside of Trump, it’s hard to think of a president who has upended and then taken over a major American party in such short order,” said William Howell, a University of Chicago political scientist.
The principal historical question: Is Mr. Trump an aberration in the parade of American presidents, or he is a precedent for future American presidents?
Either way, his size-12 footprints on the beige and navy blue carpeting with floral medallions installed in Mr. Trump’s first months in the West Wing will not soon fade.
That is a conviction his supporters embrace with fervor. It is also a view his opponents share with alarm.
“He’s been transformative if for no other reason than he radicalized a very sizable percentage of the electorate to reject the very fundamental tenets of democracy and the rule of law,” said Jon D. Michaels, a UCLA School of Law expert on presidential power. “He’s helped normalize a politics of hate, violence and corruption. And he’s helped debase and delegitimize the admittedly small number of things we’ve (for better or worse) elevated above the partisan fray — science, public health, national security, prosecutorial decisions and judicial determinations.”
No president since FDR has had remotely the impact on two branches of the American government that Mr. Trump has had.
The changes he wrought in the presidency are complemented with the changes he wrought in the bureaucracy, the result being an overhaul of the executive branch. Whether that endures is one of the principal political mysteries of the age.
But there is no question that the changes he has wrought in the judicial branch are transformative. In installing three Supreme Court justices in one term, he set the high court on a new conservative path.
In the last century, Warren Harding, Harry Truman, Richard M. Nixon and Ronald Reagan appointed four justices, but they did not alter the executive branch nearly as fundamentally as Mr. Trump. The president’s 53 circuit court appointees in four years approaches the number Barack Obama (55), George W. Bush (62) and Bill Clinton (66) placed in eight years.
Mr. Trump’s impact is all the more astonishing when his meager legislative record is compared with that of his one-term antecedent, Mr. Polk, who set out to accomplish four goals and achieved them: settling the Oregon boundary question, cutting tariffs, creating an independent treasury system as an alternative to a national bank, and acquiring California and New Mexico.
Earlier one-term presidents left behind party upheaval (William Howard Taft, Gerald R. Ford, Jimmy Carter) or economic upheaval (Mr. Hoover, the elder Mr. Bush). Mr. Trump departs with a strong stock market but high unemployment — and a virus still raging.
But it already is clear that some of the Trump initiatives will endure.
Despite promising a dramatic contrast with Mr. Trump, President-elect Joseph R. Biden Jr. likely will continue some of his policies, maintaining an aggressive posture toward China, insisting America’s NATO allies increase their defense spending, expressing skepticism about trade agreements, and building on brightening prospects in the Middle East.
Indeed, a transition memo a left-leaning assembly of progressive groups and church activists sent to the Biden team quotes these July 2019 remarks by the former vice president: “It’s past time to end the forever wars, which have cost us untold blood and treasure. Staying entrenched in unwinnable conflicts drains our capacity to lead on other issues” — words that could have come out of the mouth of Mr. Trump, who this month announced the withdrawal of most American forces from Somalia, where 700 troops have been fighting against Islamist militants.
The Yale presidential scholar Stephen Skowronek has argued that loner presidents such as Mr. Carter and John Quincy Adams (another one-term chief executive) failed to reorder the country permanently. “A great disrupter who does not set a new standard of legitimacy,” he said in a 2017 essay in The Washington Post, “will just pull things apart.”
That is the Trump conundrum, too.
The debate about Mr. Trump’s historical legacy already is underway. The debate over whether Thomas Jefferson was an authentic democrat or an authentic hypocrite has been simmering for decades. The debate over Mr. Trump’s place in history will last at least as long.