By Philip Pullella and Natalie Pompilio
VATICAN CITY/PHILADELPHIA (Reuters) - Pope Francis announced on Monday he would make his first visit to the United States next year, travelling to Philadelphia where he will celebrate an outdoor mass before an audience expected to number in the millions.
Francis ended months of speculation when he told an inter-religious conference on marriage he would go to Philadelphia in September for the Roman Catholic Church's World Meeting of Families.
He is expected to celebrate Mass on Sept. 27 in front of the Philadelphia Museum of Art, where millions of people are likely to attend, a World Meeting of Families official said.
Archbishop Charles Chaput of the Archdiocese of Philadelphia said he was "overjoyed" at the prospect of the pope's attendance at the World Meeting of Families, which convenes every three years.
"His charisma, presence and voice will electrify the gathering," Chaput said in a statement.
"As I've said many times before, I believe that the presence of the Holy Father will bring all of us - Catholic and non-Catholic alike - together in tremendously powerful, unifying and healing ways," he said.
The leader of the 1.2 billion-member Roman Catholic Church would be the fourth pope to visit the United States, the archdiocese said. Pope Paul VI was the first in 1965, followed by John Paul II and Benedict XVI.
Catholics in Philadelphia, where the archdiocese has 1.4 million members, said they were thrilled.
"I want to show him the people and what faith they have," said Joseph Micucci, 76, a deacon at the Cathedral Basilica of Saints Peter and Paul in the Center City district.
The Archdiocese in Philadelphia was hard-hit by the sex abuse scandals that rocked the Roman Catholic Church worldwide. Monsignor William Lynn, who was secretary of the clergy, was the highest-ranking clergyman in the United States to be convicted.
Lynn was found guilty of covering up child sex abuse by priests. He served 18 months in prison before his conviction was overturned.
Joe Miller, 72, who serves as an ambassador to greet visitors at the Cathedral, said he got to meet Pope John Paul II personally on his visit.
"He asked me how I was doing, shook my hand and that was it. He was a regular guy and the leader of the church," Miller said.
When Francis comes, he said, "I want to see him, shake his hand and wish him luck like anybody would."
Philadelphia Mayor Michael Nutter, at a news conference, said: "We are deeply honored that Pope Francis, the Holy Father, who is now in fact one of the world's most transformative leaders, is coming to the city of brotherly love and sisterly affection, the city of families."
The pope's trip is expected to include stops at the White House and Congress in Washington and the United Nations, but the pope did not mention those places in his address.
The World Meeting of Families, set to be held Sept. 22-27, 2015, is intended to strengthen the bonds of family worldwide, the archdiocese said. Next year would be its first meeting in the United States.
Details of the pope's visit are expected to be made public in the spring. He is likely to attend a Festival of Families event in front of the Philadelphia Museum of Art on Sept. 26, with Mass held there the following day, city officials said.
The pope is due to visit Turkey and European institutions in Strasbourg, France, in two separate trips this month. In January, he travels to the Philippines and Sri Lanka, making his second trip to Asia.
(Editing by Ellen Wulfhorst, Andrew Heavens, Doina Chiacu and Jim Loney)