A rerun of Chicago ’68? Only if Harris lets it happen.

Then, as now, the American public was growing unhappy over a war being waged far from U.S. shores. Then, it was Vietnam. Now, the Gaza Strip.

The country was as politically and socially divided in 1968 as it is now. The Rev. Martin Luther King Jr.’s assassination that April ignited riots in urban centers across the nation. Racial unrest was a simmering backdrop to the ’68 convention. Student protests were part of the regular order. Republican nominee and former vice president Richard M. Nixon was running on a law-and-order platform. Meanwhile, third-party candidate and former Alabama governor George Wallace was waging a campaign heavily coded for race.

All quite like today with our college campuses roiled by Israel-Gaza war protests. And millions of Americans disaffected from their government by the lie that the 2020 presidential election was stolen, a blatant falsehood planted and repeated by former president Donald Trump, the twice-impeached felon and Republican nominee.

Another striking parallel: The Democratic 1968 standard-bearer, Hubert Humphrey, was the vice president and a loyal supporter of a war policy that had damaged Johnson’s position with a large portion of the Democratic base. Kamala Harris, today’s vice president and Democratic nominee, is similarly situated with regard to Biden’s Gaza policies.

But here’s where the lines, one hopes, will not follow similar paths.

Many pro-Palestine protesters plan to descend on Chicago next week in large numbers. They intend to stage demonstrations that one pro-Palestinian activist, Deanna Othman, told The Post would be seen “as the equivalent of the 1968 DNC in Chicago.”

Today’s Democrats could hardly want a repeat performance of that debacle.

Thousands of antiwar activists arrived in Chicago in late August ’68 to be confronted by Chicago Mayor Richard J. Daley, who told CBS, “These people are terrorists.” “They’re against our party and against our government,” he said. Daley set out to foil demonstrators.

Violence broke out on the first day. Tear gas was in the air, clubs and rifle butts were used with abandon. TV cameras caught correspondents roughed up inside the convention hall. Democratic hopes of showing unity were shattered.

Humphrey left Chicago worse off than when he entered. He lost ground in the polls to Nixon.

That’s the last thing this year’s Democratic conventioneers need.

What followed in ’68 is no prescription for today. But on Sept. 30 in a televised speech, Humphrey pivoted on the war by promising to halt the bombing of North Vietnam as a step toward peace. Then on Oct. 31, Johnson announced a complete bombing halt and offered to negotiate peace directly with the North Vietnamese.

Still, that wasn’t enough to put Humphrey over the top. Too much intraparty bad blood over Vietnam, Eugene McCarthy’s abortive nomination bid, and broken hearts and spirits over Robert F. Kennedy’s assassination on June 5. Nixon narrowly won the popular vote but dominated the electoral college, 301 votes to 191. (Wallace won 46.)

Lot of good that did the antiwar protesters. Nixon went on to lead the nation into bloodier carnage in Cambodia.

Which is why there should be no total parallels between this year’s Democratic convention and the ’68 debacle.

What does it profit the coalition to March on the DNC to pull off a “1968 DNC in Chicago” and end up with the likes of Trump in the White House? In his debate with Biden, Trump said Biden has “become like a Palestinian,” which rights advocates rightly regarded as a slur.

“Actually, Israel is the one [that wants to keep going],” Trump said, “and you should let them go and let them finish the job. He [Biden] doesn’t want to do it. He’s become like a Palestinian, but they don’t like him because he’s a very bad Palestinian. He’s a weak one.” And Trump’s made it clear that he would roll up the welcome mat on refugees from Gaza.

So, tear up next week’s convention, fuel disarray, drag down Harris and make a second Trump administration happen. See where that gets Gaza and the West Bank.

This isn’t 1968. This country’s not going back to that. Harris has to make sure of that.

Harris is off to a late start on her presidential campaign. Biden stepped down less than 30 days ago. She’s being called upon to do everything at once. The last thing she needs is to allow her campaign to morph into infomercials for causes. Good and sound policies require thought, and a coherent, focused, well-funded and unified campaign is what’s needed to get the best policymakers to the White House. In 1968, Democrats learned that lesson the hard way.