Donald Trump couldn't have accomplished his feat without three big enablers that deserve to be held accountable for what comes next.
The first enabler has been the Republican Party.
For years the GOP nurtured the xenophobia, racism, fact-free allegations and wanton disregard for democratic institutions that Trump has fed on.
Republican fear-mongering over immigrants predated Trump, forcing Florida Sen. Marco Rubio to abandon his immigration legislation and, in 2012, pushing Mitt Romney to ludicrously recommend "self-deportation."
During this year's Republican primaries, Ben Carson opined that no Muslim should be president of the United States, and Jeb Bush and Ted Cruz suggested Syrian refugees be divided into Christians and Muslims, with only the former allowed entry.
Trump's racism is nothing new, either. Republicans have long played the race card, charging Democrats with coddling black "welfare queens" and being soft on black crime. (Remember the Willie Horton ad?)
Trump's disdain of facts is also preceded by a long Republican tradition -- denying, for example, that carbon emissions cause climate change, and that tax cuts increase budget deficits.
And Trump's threats not to be bound by the outcome of the election were consistent with the GOP's persistent threats to shut down the government over policy disagreements, and with oft-repeated calls for the nullification of Supreme Court decisions.
The second Trump enabler has been the media.
"Trump is arguably the first bona fide media-created presidential nominee," concluded a study by Harvard's Shorenstein Center on Media, Politics and Public Policy.
In March, the New York Times reported that Trump had received almost $1.9 billion of free attention from media of all types -- more than twice what Hillary Clinton had received and six times that of Ted Cruz, Trump's nearest Republican rival. The explanation for this is easy. Trump was already a media personality, and his outrageousness generated an audience -- which in turn created big profits for the media.
Media columnist Jim Rutenberg reported that CNN president Jeff Zucker was gushing over the Trump-induced ratings. "These numbers are crazy -- crazy," Zucker said.
CBS president and CEO Leslie Moonves said, "It may not be good for America, but it's damn good for CBS. ... The money's rolling in and this is fun."
Not only did the media fawn over Trump, but it failed to subject his assertions, policy proposals and biography to the scrutiny that normal candidates receive.
Fox News, in particular, became Trump's amplifier -- and Fox host Sean Hannity became Trump's daily on-air surrogate.
Trump also used his own unceasing tweets as a direct, unfiltered, unchecked route into the minds of millions of voters. The term "media" comes from "mediate" between the news and the public. Trump removed the mediators.
The third Trump enabler has been the Democratic Party.
While Republicans played the race card to get the working class to abandon the Democratic Party, the Democrats simultaneously abandoned the working class, clearing the way for Trump.
Democrats have occupied the White House for 16 of the last 24 years, and for four of those years Democrats had control of both houses of Congress. But in that time they failed to reverse the decline in working-class wages and jobs.
Both Bill Clinton and Barack Obama ardently pushed for free trade agreements without providing millions of blue-collar workers who thereby lost their jobs means of getting new ones that paid at least as well.
They stood by as corporations hammered trade unions, the backbone of the white working class. They failed to reform labor laws and to impose meaningful penalties on companies that violate them.
Partly as a result, union membership sank from 22 percent of all workers when Bill Clinton was elected president to fewer than 12 percent today, and the working class lost bargaining leverage to get a share of the economy's gains.
Clinton and Obama also allowed antitrust enforcement to ossify -- with the result that large corporations have grown far larger, and major industries more concentrated.
The unsurprising result has been to shift political and economic power to big corporations and the wealthy, and to shaft the working class. That created an opening for demagoguery, in the form of Trump.
On his way to the White House, Donald Trump poisoned America. But he didn't do it alone. He had help from the GOP, the media and the Democratic Party.
The pertinent question now, in the age of Trump, is: What, if anything, have these enablers learned?
(Robert Reich, a former U.S. Secretary of Labor, is professor of public policy at the University of California at Berkeley and the author of "Saving Capitalism: For the Many, Not the Few," now available in paperback. His new film, "Inequality for All," is now out on Amazon, DVD and On Demand. His daily blog is at www.facebook.com/RBReich/.)