It is expected a crowd of 1.5 million people will turn out to see Pope Francis celebrate mass in Philadelphia this evening.
It will mark the end of the pontiff's three-city tour of the United States.
Earlier this week, Pope Francis addressed Congress in Washington, as well as the United Nations General Assembly in New York.
He also met with US president Barack Obama.
Reporter Amanda Walker is in Philadelphia, and says the visit has been a success:
Last night Pope Francis also spoke at the Festival of Families in the city, with actor Mark Wahlberg and singer Aretha Franklin among the well-known performers taking part in the event.
The pontiff had this message for the thousands of people in attendance:
"Let us help one another to make it possible to 'stake everything on love'. Let us help one another at times of difficulty and lighten each other’s burdens. Let us support one another. Let us be families which are a support for other families," he added.
