Pope Francis delivers a Mass at the World Meeting of Families at Benjamin Franklin Parkway in Philadelphia on Sunday. The Associated Press

Pope Francis, center, celebrates Mass Sunday. The Associated Press

Hundreds of thousands gather to celebrate Mass with Pope Francis Sunday. The Associated Press

An unidentified child, who was carried out from the crowd to meet Pope Francis, reaches out to touch the Pontiff's face during a parade on his way to celebrate Sunday Mass on the Benjamin Franklin Parkway in Philadelphia, Sunday. The Associated Press

Pope Francis greets the gathered crowds along the Benjamin Franklin Parkway, Sunday. The Associated Press

Pope Francis acknowledges faithful as he parades on his way to celebrate Sunday Mass on the Benjamin Franklin Parkway Sunday. The Associated Press

Pope Francis blesses a cross for Maribel Rivera, an employee at the Curran-Fromhold Correction Facility in Philadelphia,. The Associated Press

Pope Francis greets corrections officers at the Curran-Fromhold Correctional Facility in Philadelphia on Sunday. The Associated Press

Archbishop Charles Chaput, left, and Bishop Timothy Senior, right, listen as Pope Francis, addresses a gathering in Saint Martin's Chapel at St. Charles Borromeo Seminary on Sunday in Wynnewood, Pennsylvania. The Associated Press

Juan Baptista, of Costa Mesa, Calif., drums on a bongo while wearing a T-shirt bearing the image of Pope Francis as he sings with his church group along Benjamin Franklin Parkway ahead of Francis' parade and Mass Sunday, Sept. 27, 2015, in Philadelphia. (AP Photo/David Goldman)

Pope Francis speaks to inmates during his visit to the Curran Fromhold Correctional Facility in Philadelphia on Sunday. The Associated Press

A sister with the Missionaries of Charity, from Toronto, uses a piece of paper with the images of Pope Francis to shade her eyes to better see the huge monitor on the Benjamin Franklin Parkway in Philadelphia. The Associated Press

Pope Francis receives a chalice from Bishop Timothy Senior, right, after addressing a gathering in Saint Martin's Chapel at St. Charles Borromeo Seminary on Sunday in Wynnewood, Pennsylvania. The Associated Press

Francisco Estrada, of Prince Island, Pennsylvania, wearing his ticket around his neck, holds a stuffed Pope Francis doll before the pope arrives to celebrate a final Mass on the Benjamin Franklin Parkway on Sunday, The Associated Press

Pope Francis greets inmates during his visit to Curran Fromhold Correctional Facility in Philadelphia on Sunday. The Associated Press

Pope Francis touches a woman in a wheelchair after he addressed a gathering in Saint Martin's Chapel at St. Charles Borromeo Seminary on Sunday in Wynnewood, Pennsylvania. The Associated Press

Rebecca Granado, a nun from Topeka, Kansas, reads her bible as first year seminarian Dustin Vu, 20, from Orange County, California, stretches out on the ground to mediate and pray as they both wait along the Benjamin Franklin Parkway in anticipation for Sunday's Papal Mass in Philadelphia. The Associated Press

A family from Trenton, New Jersey,, originally from Ecuador, walk over the Benjamin Franklin Bridge ahead of a Sunday Mass to be delivered by Pope Francis in Philadelphia. The Associated Press

A nun from The Sisters of Life, of New York City, is inspected at a security checkpoint as she arrives for a Mass to be celebrated by Pope Francis on Sunday in Philadelphia. The Associated Press

A nun watches Pope Francis on a big screen as police stand in formation on the Benjamin Franklin Parkway, Sunday, Sept. 27, 2015, in Philadelphia. (AP Photo/John Minchillo)

Pope Francis gives a blessing to Gerald Buck, an employee at the Curran-Fromhold Correction Facility in Philadelphia, center, during his visit there Sunday, Sept. 27, 2015. (Todd Heisler/The New York Times, Pool)