Philadelphia is hosting the World Meeting of Families in September 2015. Philadelphia Archbishop Charles J. Chaput and Archbishop Vincenzo Paglia, head of the Pontifical Council for the Family, signed documents Tuesday sealing the choice of Philadelphia.
While Francis is expected to attend the world meeting, any official announcement is months away. He is likely to make it part of an extended trip to the United States.
Chaput said the trip has a number of purposes, saying it "boosts us back home" by increasing the commitment of both clerical and secular leaders. Corbett said that meeting with Vatican officials also gives the state and city a better idea of what the Vatican needs from them.
The official invitation to the pope has to come from President Obama, who will be in Rome this week.
The Philadelphia delegation arrived Monday and plans to stay through Thursday. They spent some time Monday after an overnight flight sightseeing in Rome.