Donald Trump’s election has been greeted by a considerable portion of the country with panic.

Large swaths of commentators have described his victory as a potential disaster for the nation — placing a “xenophobic racist” and “clown” in the Oval Office.

One Hillary Clinton supporter outside her hotel in New York the morning after the election said, “I’m feeling physical pain. I’m shocked. I’m sad.” Articles with headlines like “Day of Mourning,” “An American Tragedy” and “Autocracy: Rules for Survival” have bounced across the Internet. As the New Yorker’s David Remnick wrote, “This is surely the way fascism can begin.”

At times like these, it helps to look to our past for perspective. And the truth is that we’ve been here before, many times, throughout the 19th century and in living memory.

In 1968 and 1980, the same liberal, educated and urban swaths of the country voiced similar fear and despair about the outcome — a sense that the nation as they knew it could not survive. And yet here we are, decades later, still enamored with the republic they were sure was doomed.

When Richard Nixon was elected in 1968, he had been in public life for more than 20 years, and he cultivated a reputation as a staunch, unyielding ideological Cold Warrior who had little but contempt for liberals and elites. He advocated for the “silent majority” and had little interest in minorities. As a congressman in the 1940s, he led the House Un-American Activities Committee to root out suspected communists. He became Eisenhower’s vice president almost entirely because of his rigid conservative credentials. Nixon was at times respected but rarely liked by the public, his adversaries or even by his allies.

advertisement | advertise on newsday

On the eve of his election in 1968, the United States was bitterly divided and teetering on the edge of violence. There were riots outside the Democratic National Convention, and nationalist proto-Trump third-party candidate George Wallace was ascendant.

When Nixon squeaked into office with a tiny margin, liberals and the left despaired.

As the late liberal senator Paul Wellstone (D-Minn.) recounted in his memoirs, the reaction in his household was simple: “Nixon is a fascist pig.”

When Nixon won reelection in 1972, Hunter S. Thompson recalled bewildered Democrats quoting from the book of Jeremiah after the debacle, saying that “the harvest is past, the summer is ended, and we are not saved.” They looked bleakly at long years in the wilderness, not realizing that Watergate and the eviction of Nixon were but a season away.

The election of Ronald Reagan in 1980 was greeted on the left with no less pain and fear. Like Nixon, Reagan ran as a Cold Warrior, which also meant running against the elites who were seen as too soft — on dangers abroad and on crime, lawlessness and moral decay at home.

One Cornell activist and supporter of incumbent Democrat Jimmy Carter spoke for millions when he said Nov. 5, 1980: “The election of Ronald Reagan is a disaster for the country because he’s a fascist. He’s a dangerous person.”

I can vividly remember my high school history teacher walking dazed through the corridors convinced that the end of the republic was at hand, a phrase he muttered throughout the coming days in dead seriousness.

Coretta Scott King confessed that she was “scared” of Reagan as president, worried that it would mean tailwinds for the Ku Klux Klan. As historian Gil Troy observed, opinion polls showed that the electorate liked neither Reagan nor Carter, but liberal vehemence toward Reagan was particularly acute. Sound familiar?

Reagan attributed his victory to his promise “to put Americans back to work” and to make the country stand tall and proud on the global stage after the humiliations of the Soviet invasion of Afghanistan and the Iran hostage crisis. When asked why he won, he said simply that when people looked at him, “they saw themselves and saw that I’m one of them.”

Much the same could be said of Trump. And, in many ways, the American picture improved under Reagan, as it might have regardless of who was in the Oval Office but that redounded to his credit.

advertisement | advertise on newsday

Economic growth accelerated; the Soviet Union began to stumble and then crumble; and the public mood brightened considerably, even as Reagan filled his cabinet with cronies of questionably aptitude such as Edwin Meese in the Justice Department and the deservedly forgotten James Watt at the Interior Department, who proceeded to rail against women and minorities filling his department.

You can argue about how destructive or constructive Nixon and Reagan proved to be. You cannot credibly argue that the nation’s foundations were acutely tested by their presidencies, which was precisely what liberals firmly believed after the election wins.

Watergate indeed strained the country, but the system bent and didn’t break. The fears then and the fears now sound the same and, if memory serves, felt the same. And similar forces were in play: Angry men from the heartland were the core of both electoral waves, the core of Nixon’s base in 1968 and in 1972 and of Reagan’s in 1980. They bore, as well, a similar animus to the liberals and elites and wealthy of the coasts and cities.

Every story is different, but we have been here before.

Maybe not with the expansive powers of the post-Cold War imperial presidency, maybe not with the same echo chamber of social media, but even so. We have been bitterly, ragefully divided between them and us, and had Hillary Clinton won, 59 million voters would have felt just about what 59 million voters feel today: that truly churning combination of disgust and dread at who will be the next president.

advertisement | advertise on newsday

Trump has promised to upset the norms that have governed Washington. He has tapped into dark anger to an exceptional degree. And, yes, in other countries at other times, that has been the first step on an ugly road.

Could it happen here? Sure, it could. But possible isn’t probable, and we have danced this dance before.

He has a mandate to break a system that in many ways is broken; few of us disagree that Washington is in deep need of something other than the way things have been. There are risks there and danger, but if past is at all prologue, we will find that the sum of all our fears amounts to far less than many of us just now believe.

Karabell is the head of global strategy at Envestnet, a financial services firm, and the author of “The Leading Indicators: A Short History of the Numbers That Rule Our World.”