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Pope Francis' confirmed Monday that his trip to the United States this fall will include stops in Washington and New York City, in addition to the previously announced visit to Philadelphia.

The pontiff told reporters he wishes he could enter the U.S. through the Mexican border "as a sign of brotherhood and of help to the immigrants," but will probably just fly directly to the East Coast.

"You know that [to] go to Mexico without going to visit the Madonna [of Guadalupe] would be a drama. A war could break out," he said, laughing. "I think there will only be those three cities. Later there will be time to go to Mexico."

Details of his itinerary are in the early-planning stages, but organizers are already talking about appearances at the White House, the United Nations and Ground Zero, and even a Mass at Madison Square Garden.

One thing that is not in question: American Catholics can't wait to play host to the hugely popular people's pontiff.

"You can't go to anything connected to the Archdiocese without people asking if Pope Francis is coming," Joseph Zwilling, a spokesman for the Archdiocese of New York, told NBC News on Monday.

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Zwilling said he was in New York for Pope John Paul II's second visit in 1995 and for Pope Benedict XVI's trip in 2008 but thinks "a visit by Pope Francis is going to easily surpass either of those two events."

New York Mayor Bill de Blasio said the city will welcome the 79-year-old leader of the world's Catholics "with open arms."

"Pope Francis is the leading global voice on issues of social justice and income inequality, and New Yorkers from all backgrounds will be tremendously humbled and honored to hear his message right here," de Blasio said in a statment.

The pontiff, who just completed a record-shattering visit to the Phillippines, had already committed to traveling to Philadelphia in September for the World Meeting of Families, but had not announced any other stops.

Archbishop Bernadito Auza, who was in Manila with the pope last week, told the Catholic News Agency that a U.S. committee has been drawing up a proposed schedule but the Vatican has not signed off on anything.

The United Nations General Assembly will be in session the week of the visit, which will give the pope the chance to address many of the world's leaders while he is in New York.

Benedict already visited Ground Zero, but the 9/11 memorial and museum has opened since then. Depending on how long Francis is in New York, he could say Mass, and Madison Square Garden has been mentioned as a possible venue, organizers say.

"To enter the USA from the border of Mexico would be a beautiful thing, as a sign of brotherhood and of help to the immigrants."

The pope said he plans to celebrate Mass at Washington’s Basilica of the National Shrine of the Immaculate Conception so he can canonize American missionary Junipero Serra, who brought Christianity to the western United States.

"I would like to go to California for the canonization of Junipero, but I think there is the problem of time," he told reporters.

He did not say whether he would visit the White House, but Auza said there would likely be a welcoming ceremony there.

In Philadelphia, the Pope is set to say Mass and conduct a prayer vigil during the families meeting. He will also visit either a children's hospital or a juvenile prison, the archbishop said.

Pope Francis' humility and populism has won him fans around the globe. Among U.S. Catholics, his approval rating was 88 percent in a December poll by Saint Leo University. Six out of 10 non-Catholics had a favorable view of the pope.