Irish eyes were smiling Friday outside a sitting president’s home for the first time in New York history.

Unprecedented security was in place outside President Donald Trump’s namesake tower on Fifth Avenue between 56th and 57th streets, on the parade route.

The parade — which dates to 1762 — stepped off at 11 a.m. at 44th Street, moving north to 79th Street, where it is expected to end at 4:30 p.m.

New this year: a police-enforced restriction prohibiting cars from crossing Fifth Avenue during breaks in the parade.

Presiding early Friday morning over an annual St. Patrick’s Day breakfast at Gracie Mansion, Mayor Bill de Blasio implicitly criticized Trump’s immigration policies without mentioning the president’s name.

Trump has signed executive orders to temporarily stop the entry of immigrant, refugees and visitors from six Muslim -majority countries deemed terror threats. Implementation of the orders has been halted by federal judges hearing challenges to their constitutionality.

Standing at a lectern in front of flags of New York City, the United States and Ireland, de Blasio, a Democrat, likened the plight of new refugees to that faced by Irish immigrants to America in the 19th and 20th centuries, when they encountered discrimination and bigotry.

“Not a welcome. Not a sense that these were, in effect, refugees fleeing something horrendous, but they were treated like the wretched. And we have to remember that history, and there’s that famous saying, to know history so you don’t repeat it?” de Blasio said in remarks to several hundred people. “We have to respect each and every new generation that joins us from all over the world.”

De Blasio was expected to march in the parade, as were Gov. Andrew M. Cuomo, City Council Speaker Melissa Mark-Viverito and Ireland Prime Minister Enda Kenny.

Organizers expected about 100,000 marchers and up to 2 million spectators. The Long Island Rail Road is running an additional six westbound trains and 10 eastbound trains. Alcohol is banned on trains, stations and platforms until 5 a.m. Saturday.

The family of Steven McDonald, the police officer paralyzed in a shooting 1986 by a gunman who died in January, marched in his honor behind police bagpipers.

“This is probably my brother’s favorite day of the year, and he marched no matter what the weather,” said his sister Theresa Wadkins of Rockville Centre as parade-goers cheered.

“We pushed him up Fifth Avenue, and the people of New York showed their love for him every year,” Wadkins said. “He’s not with us in his chair today but he is with us in spirit. All these people love him and remember him and will always remember him.”

His son, Conor McDonald, an NYPD sergeant from Malverne, said the family wanted to recall his father’s philosophy of love and forgiveness. The elder McDonald man forgave the teen shooter.

A banner the carried by the family was meant to highlight, “everything my dad was all about — love and forgiveness,” Conor McDonald said.

Mary Dooner, a dental office manager from upstate Middletown, stood at the end of the parade route, ahead of her husband, who marched with the Ancient Order of Hibernians.

Clad in a green top and bundled against the cold, Dooner recalled her Irish ancestors who came to America from Cork and Waterford, and the heritage the parade celebrates.

“I enjoy seeing the children. I walked the whole parade route,” she said. “It’s my exercise for the day — and my last exercise for the day.”

At the breakfast at Gracie Mansion earlier in the day, de Blasio praised the Irish prime minister, who during a meeting this week with Trump discussed the status of the estimated 50,000 undocumented Irish in the U.S.

“I think he did a great service to America by making his comments — by reminding us all that those who come here, for whatever reason and in whatever status, look like the entire world just like the great history of American immigration tells us, and they are human being yearning to breathe free,” de Blasio said of Kenny.

De Blasio had boycotted the parade until last year, when gays marching under their own banner were permitted for the first time under an agreement brokered by the Irish consulate to New York.