The 78-year-old Argentine pope had been practicing over the summer, but is still not comfortable speaking in English.
Tickets were distributed through parishes in New York City and New York state.
Congressman Michael McCaul said that other potential threats are being monitored "very closely."
The prisoners were released as gesture of goodwill before the pope's arrival.
On Tuesday, the pope will release decrees to reform the marriage-ending process.
Catholic women denied the right to enter the clergy are taking matters into their own hands.
Meanwhile, Israel debates its response to refugee crisis.
New polling by Pew Research Center shows Catholic attitudes on key social issues are increasingly liberal.
Ahead of his announced Holy Year of Mercy, the pope wrote about "the tragedy of abortion."
Paraguayan law permits abortion if a mother's life is endangered. Pope Francis last year called abortion "horrific," and has shown no signs of changing the Catholic Church's position.
Environmentalists say Ecuador's leftist leader, Rafael Correa, gives a greater priority to business.
The pope puts it very plainly to leaders who might be laggards: It’s time to face climate change.
In what Vatican officials are calling "a heinous act," the Italian magazine "L'Espresso" leaked a draft of the hotly anticipated papal encyclical on the environment.
The creation of the tribunal is the biggest step the Vatican ever has taken to hold bishops accountable.
The pope apparently never even saw an episode of "Friends."
Faced with an onslaught of questions, the Vatican rebutted what it called erroneous media reports.
The move highlights Pope Francis' drive to help embattled Christian communities in the Middle East.