Some 15 long years after the horrors of 9/11, much of America remains trapped in a 9/10 mindset. The latest evidence involves the alleged bomber who wreaked havoc in New York and New Jersey last weekend.

The blood ran when the Chelsea blast injured 29 people, but now come reports that make the blood boil: The feds failed to connect the dots that might have prevented the weekend from hell.

The reports reveal several critical facts, starting with the most important: The father of alleged bomber Ahmad Khan Rahami called law enforcement authorities in 2014 and said his son was a terrorist.

The New Jersey police turned the information over to the FBI, and agents interviewed the father, the New York Times reports. But when the father recanted his charge, the bureau apparently closed the case.

Yet we now know that Rahami had visited Pakistan and Afghanistan several times for extended periods before and after 2014. One trip lasted for 13 months, CNN reports, and another involved a stay in Quetta, Pakistan, a notorious hotbed of the Taliban and other terror groups that is so dangerous, the Pakistan army avoids it.

One result of those trips was that Rahami became a devout Muslim, a childhood friend told The Post.

“He had changed,” Flee Jones said. “He dressed differently, more religiously, the robe and everything.”

The feds missed other signs, too. Rahami posted radical Islamic writings on a personal website, DNAInfo reports.

And when he was captured, Rahami was said to be carrying a notebook containing his pro-jihadist writings, including references to the Boston Marathon bombers and Anwar al-Awlaki, a US-born cleric who became a top al Qaeda recruiter before being killed by an American drone.

None of these revelations tarnishes the fast, fabulous work of police and federal agents in New York and New Jersey after the bombings.

Their quick apprehension of Rahami was a marvel of technology, anti-terror training, including with robots, and old-fashioned shoe-leather work, with some luck thrown in. Other attacks may have been blocked as a result.

But too many dots were missed before the bombs went off.

Imagine, for example, if the FBI had gone beyond interviewing the father to learn that Rahami had been to Muslim countries teeming with terrorism. Would it still have closed the case?

Imagine if agents had followed his digital trail and uncovered his Islamist leanings. What if they knew he praised the Boston Marathon bombers — who also turned pressure cookers into bombs?

The questions are fair given the previous cases in which people who turned out to be terrorists had been flagged, but dropped off the radar, only to resurface with lethal attacks.

That describes the Tsarnaev brothers, who bombed the 2013 marathon. The FBI had a tip from Russia that the older brother, Tamerlan, was radicalized during a trip to Dagestan, a largely Muslim republic wracked by war and terrorism.

Agents investigated, found no evidence, and closed the case, without notifying Boston police.

Then there’s the 2009 Fort Hood shooter, Nidal Hasan, an Army major and psychiatrist who killed 13 people, despite the fact that superiors knew he talked of jihad and also had communicated with Anwar al-Awlaki. Again, no action was taken — until after he left a trail of corpses.

These are not new lessons. The discovery that authorities had failed to connect the many dots of suspicion about the perpetrators of 9/11 led to numerous pieces of legislation and repeated vows that it would never happen again.

But it’s still happening, again and again. Even though no attack has rivaled 9/11 for mass casualties, and even though a heightened law enforcement awareness has disrupted many plots, it is hard to escape the conclusion that some successful attacks could have been prevented.

Simple errors and incompetence cannot be ruled out, but it is clear that political correctness is handcuffing law enforcement.

While it is wrong and illegal to stereotype all Muslims as terrorists, that standard need not hamper legitimate investigations, especially when signs of radicalization are obvious.

As others have noted, the American Constitution is not a suicide pact. Law enforcement is not required to close its eyes to evil.

To do so, to give in to false claims of Islamophobia, trades one mistake for another. And too many innocent Americans have paid for that mistake with their lives. How many more must die from political correctness?

Caught in Chrisfire

For bombshell allegations, it’s hard to top what federal prosecutors said on the opening day of the Bridgegate trial: that Gov. Chris Christie knew all along that aides intentionally caused massive traffic jams on the George Washington Bridge to punish a local mayor who refused to endorse the governor.

It is also hard to top the allegation for unfairness. If the feds think Christie was in on a plot, why wasn’t he charged? And why wait until the trial, three years after the event, to make such a damning charge about a public official?

The trial prosecutor, Vikas Khanna, must have expected those questions because he tried to brush them aside by telling the jury its only job was to rule on the charges against the two former Christie aides on trial. The jury, Khanna said, should ignore everyone else.

That’s not easy to do, especially with defense lawyers also arguing that Christie knew in advance. The tactic makes perfect sense for them, but not for prosecutors.

It could undercut their case by suggesting to the jury the ringleader remains free, and adds to the impression they are on a political witch hunt. Christie is a GOP governor in a blue state, and it boggles the mind to think a traffic jam, whatever its cause, is a federal crime. Name a day when there isn’t a jam on the GW.

Indeed, New York City officials boast about closing lanes, which creates endless snarls. Is that a crime?

Predictably, the New York Times pinned the Christie allegation on Donald Trump’s chest, using the two men’s relationship to further its disgraceful efforts to derail Trump’s campaign.

It would be an even greater disgrace if prosecutors are playing the same game.

Until they explain themselves, they are presumed guilty.

Going out a Vinner

Vin Scully, the beloved broadcaster who grew up in The Bronx, started calling games for the Brooklyn Dodgers in 1950, followed the team to Los Angeles in 1957 and is about to put down his microphone for the last time, had this to say about his remarkable longevity: “I attribute it to one thing and one thing only: God’s grace to allow me to do what I’ve been doing for 67 years. To me, that’s really the story.”

Obama criticized America 11 times in his UN speech . . .

Only 11 slurs this time?

Either Dear Leader is tired, or he isn’t as disappointed in his lowly subjects as he used to be.