One way or another, Nancy Pelosi will go down in history. Let’s hope she doesn’t take America with her.

The speaker’s decision to go all in on impeachment is fraught with danger and could have fateful consequences far beyond Donald Trump’s presidency. With only about a year to go until the 2020 election, Pelosi has thrown her full weight behind the effort to undo the results of 2016.

This is a historic mistake, one that could tear America apart. Based on the evidence the House has made public, impeaching Trump is a meritless, reckless assault on democracy.

Anyone who believes our country is now a polarized tinderbox ain’t seen nothing yet. Trying to remove the president on the flimsy charges that he illegally pressured Ukraine for investigative help would quicken the national crack-up that’s been building for years.

Pelosi’s timing is both cynical and bizarre. A full House vote on an impeachment inquiry, which could come Thursday, probably means she is aiming to consider articles of impeachment this year.

The rush suggests an acceptance of the reality that there will be nothing in those articles that would sway 20 Senate Republicans needed for conviction and removal, so the aim is to please the radicals in her own party and be done with it as soon as possible. Thus, Pelosi is ready to throw America into chaos simply as a political favor to the Democrats’ wing-nuts so they won’t run primaries against her leadership team and committee heads.

Pelosi isn’t leading, she’s following.

Why doesn’t she just step aside and let Reps. Alexandria Ocasio-Cortez and Ilhan Omar run the party? They would probably start by declaring war on Israel.

Pelosi’s pandering to the kooks mocks the gravity of the impeachment provision and makes rank partisanship her sole agenda. Instead of working with the Senate and White House on legislation that might move the nation forward, she chooses to take it backward and risks igniting a violent spasm of tribalism.

In a “Dear Democratic Colleague” letter Monday, she couched her choice as the best way to combat the White House’s refusal to cooperate with the demands for testimony and documents from six different committees. In fact, those committees already are fashioning an impeachment case, much of it in secret, while trying to avoid a formal public vote to protect their vulnerable colleagues in swing districts.

Forced by Trump to take the public vote or fight the authority issue in the courts, Pelosi responded by effectively accusing the president of refusing to cooperate with a lynch mob. Her solution is to give the mob a plastic badge to make it legal.

Her real problem is that she doesn’t have the goods to justify impeachment under any process. And she won’t, no matter how many witnesses emerge from the bureaucracy to say they were unhappy with the Ukraine call or didn’t agree with Trump’s choices. Policy disagreements and murky arguments won’t lead to a public consensus for removing an elected president.

In truth, Pelosi cornered herself in late September. That’s when she unleashed the committee probes and used the i-word, saying Trump was guilty of a “betrayal of his oath” and “must be held accountable.”

The next day, the White House released the transcript of the Ukraine call. While it wasn’t “perfect,” as Trump insists, the call was not even close to a “high crime and misdemeanor” by any reasonable standard.

Still, until Monday, Pelosi had an off-ramp. She could have let the investigations continue to see if evidence emerged that Trump had committed some other clear and compelling violations of law. If nothing emerged, she could have let the probes quietly die of boredom and inattention.

Now, with a plan for public hearings and fiery cross-examination, she has zero alternative to producing and passing articles of impeachment and sending them to the Senate for trial. As it stands now, the trial will fail by a wide margin — 67 votes are need for conviction — and Trump will legitimately be able to claim vindication.

If that weren’t trouble enough for Dems, there is now another X factor — the Justice Department’s review of the origins of the 2016 spying on the Trump campaign is now a criminal investigation. Any prosecutions against the likes of James Comey, John Brennan and James Clapper would mark a complete comeuppance for Barack Obama’s administration.

Imagine the impact of that on the 2020 race. It would be a final nail in the candidacy of former Obama veep Joe Biden and force the eventual nominee to defend the party’s dirty tricks of 2016.

Good luck with that burden.

As for Pelosi, she is betting the country in a grubby bid to hold on to power. History will not be kind to her.

Blas fails homeless children

From Post reporter Selim Algar comes more evidence of the decline of New York and the failure of Mayor Bill de Blasio. Algar writes, “The number of homeless city schoolkids hovered near staggering record highs in the last academic year, topping 100,000 for the fourth consecutive period, according to a new report.

“Citing data from the state Education Department, Advocates for Children of New York found that 114,085 public and charter students — or 1 in 10 — identified as homeless. Of those, 34,000 resided in city shelters and 73,750 were living in temporary housing with relatives, friends or other acquaintances.”

The head of the agency put it this way: “The number of students who experienced homelessness last year — 85 percent of whom are black or Hispanic — could fill the Barclays Center six times.”

And de Blasio wanted to be president. Imagine the damage he would do to America.

Left vs. left? All right!

New York Dems can’t handle success. Less than a year after taking full control of Albany, their simmering civil war is bursting into the open.

The Working Families Party issued a full-frontal attack on Gov. Andrew Cuomo on Tuesday, accusing him of wanting to help Republicans at its expense. Now that’s a low blow!

It seems Cuomo’s handpicked head of the state Democratic Party wants to make it harder for smaller parties to keep their ballot lines. Instead of needing at least 50,000 votes, the number would rise to 250,000.

“We know Andrew Cuomo’s politics, we knew a sneak attack like this was coming,” the WFP said in a fundraising pitch. It said Cuomo “prefers divided government, where he can bottle up progressive legislation and be the kingmaker in every deal.”

I’m guessing Cuomo won’t stay silent. This could be fun.

Boulder action!

After a 1-ton boulder called Wizard Rock was stolen from an Arizona national forest, a federal official told Fox News that “our hope is that it will be returned to us, and these recent recurring events will become an educational opportunity.”

Suggestion: Hunting down the perps and locking them up would be a far better education.