NEW YORK — In a stunning upset, Republican Donald Trump Wednesday morning was elected to become the 45th president of the United States — ending a dramatic campaign by assuring voters he would seek to unify a broken country.  

“The forgotten men and women of our country will be forgotten no longer,” Trump told to an explosive crowd of his supporters. “Now it’s time for America to bind the wounds of division. It is time for us to come together as one united people.” 

Coming into Election Day, Trump seemed set to lose to Democrat Hillary Clinton, after national polls showed her up more than 3 percent nationwide. But as the night progressed, Trump pulled off the seemingly impossible: he won Florida, North Carolina, Wisconsin and Pennsylvania — all battleground states he needed to surpass 270 electoral votes. 

At the Hilton Midtown, where Trump booked his “Victory Party,” a jubilant crowd erupted in cheers for the New York businessman. Throughout the night, the crowd grew steadily more excited as battleground states awarded their electoral votes to Trump in scores.  

When Fox News — broadcast on TVs all around the hotel — announced the news early Wednesday morning, the Trump supporters went wild. 

“This is the best day of my life,” said Jorge Pellegrino, a New York native who attended the event. 

David Rothschild, an economist at Microsoft Research who runs PredictWise, an online forecasting model, had predicted an overwhelming Clinton win. But after a “relentless media pursuit” undermined her credibility, he said, young voters flocked to third party candidates and may have cost Clinton the election.

Libertarian Gary Johnson and Green Party nominee Jill Stein performed strongest among under-30 voters, gaining 5 percent and 2 percent of the group’s vote, respectively.

“Obviously 16 years later, the lessons of Ralph Nader (who took votes away from Al Gore in 2000, many say) were lost on the younger generation,” Rothschild said. “They saw an equivalent, bad set of choices, and voted third party.”

Rothschild said lack of enthusiasm for Clinton among young voters in key battleground states added to her troubles. Clinton won support from 18 to 29-year-olds by only 55 percent compared with President Barack Obama’s 66 percent in 2008.

Young women, however, overwhelmingly backed Clinton 63 percent to Trump’s 31 percent.

Late Wednesday morning, when Clinton officially conceded the “painful” election to her Republican rival, she addressed those women directly.

“To all the women, especially young women … nothing has made me prouder than to be your champion,” she said, her voice cracking with emotion. “We have still have not shattered that highest and hardest glass ceiling. But some day, someone will.”

Photos by David Fishman/MNS