Pope Francis flew over New York's Statue of Liberty and the former immigration station of Ellis Island aboard a helicopter on Saturday, in an unscheduled detour that gave him nostalgia for his home town Buenos Aires.

Flying to JFK International Airport to take a plane to Philadelphia, the pope asked the helicopter pilot to circle the landmarks, New York's Cardinal Timothy Dolan said.

"You could see he was very, very moved," Dolan told reporters. "And he said 'You know, Buenos Aires was a city of immigrants too,'" Dolan said.

The son of an Italian immigrant family and the first Latin American pope, Francis has taken up the plight of immigrants as one of the main issues of his papacy, along with climate change, economic equality and religious freedom.

On Thursday, the Argentine pontiff urged Americans in a historic speech to Congressto reject "a mindset of hostility" toward immigrants.

In Philadelphia later on Saturday, he will address Hispanic immigrants in a speech in Spanish at the site of Independence Hall, the 18th century red-brick building where the United States' two bedrock documents, the Declaration of Independence and Constitution, were adopted.

Some two hundred local parishioners and church officials offered the pontiff a show of gratitude for his visit to New York by gathering near his plane on the tarmac of JFK.

One of them, Gabriela Munoz, 42, of Brooklyn, an undocumented immigrant from Mexico, became emotional while speaking of the pope's comments on immigration, which she said had given her "a lot of hope and faith."

TIRED POPE STUMBLES

Following an arduous schedule in New York and Washington on the back of a four-day trip to Cuba, the 78-year-old Francis

stumbled several times as he climbed the stairs of the American Airlines jet taking him from JFK to Philadelphia.

But he smiled and waved once he reached the airplane door, apparently in good shape, and the plane took off.

Vatican spokesman Father Federico Lombardi acknowledged to reporters on Friday night that the pope was tired amid a packed schedule. He said the pope usually has physical therapy for a leg problem but cannot undergo therapy during trips so was having some difficulty with steps.

Cheering crowds greeted Francis in Philadelphia on the penultimate day of his first visit to the United States when he arrived at the Cathedral Basilica of Saints Peter and Paul for a Mass.

On his visit to the city, the birthplace of American independence, Francis will promote religious freedom, an issue close to the hearts of both Catholic conservatives and American Evangelicals who fear the encroachment of the secular world in public life.