When Philadelphia was first announced as the site, Pope Benedict XVI he said he planned to attend. Speculation has been building as to if Francis will also go, though popes don't always attend the meetings, which began under Pope John Paul II.
Since the United Nations General Assembly in New York tends to take place in September, Francis might also make a visit there for an address.
Like previous popes, Francis has made it clear in his nearly year-old papacy that he plans to visit many areas of the world. In July, the pope greeted millions of pilgrims at World Youth Day in Rio de Janeiro, Brazil. That same month, he celebrated Mass in Lampedusa, an Italian island, where he commemorated the lives of thousands of African migrants who have died trying to cross the sea into Europe through the island. In May, the pope will visit Amman, Bethlehem and Jerusalem, and the Vatican has said that the pope wants to visit South Korea in August.
The Vatican and Philadelphia archdiocese have not officially confirmed the U.S. visit.