KEVIN LAMARQUE/REUTERS

Pope Francis is visiting Washington, New York City and Philadelphia during his first trip to the United States. The Pope is the first leader of the Roman Catholic Church to address a joint meeting of Congress, including more than 500 lawmakers, Supreme Court justices and top administration officials including Vice President Joe Biden, September 24, 2015.

President Barack Obama (R), first lady Michelle Obama, and Pope Francis wave from a balcony at the White House in Washington, D.C., September 23, 2015.

Pope Francis at U.S. Capitol

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Pope Francis bids farewell to Secretary of State John Kerry as he departs from Washington, D.C. en route to New York City on September 24, 2015 in Joint Base Andrews, Maryland.

Pope Francis at U.S. Capitol

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Spectators on the West Front of the U.S. Capitol building react as Pope Francis makes an appearance on the West Front Speaker's office balcony in Washington, D.C, September 24, 2015.

Pope Francis is the first pope to address a joint meeting of Congress and will finish his tour of Washington later in the day before traveling to New York City.

Pope Francis at U.S. Capitol

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Pope Francis waves to the crowd from the Speakers Balcony at the Capitol in Washington, D.C., September 24, 2015.

Pope Francis at U.S. Capitol

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Spectators on the West Front of the U.S. Capitol building watch a telecast of Pope Francis addressing a joint session of U.S. Congress on September 24, 2015 in Washington, D.C.

Pope Francis at U.S. Capitol

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Pope Francis addresses a joint meeting of Congress in the House Chamber of the U.S. Capitol on September 24, 2015 in Washington, D.C.

Pope Francis at U.S. Capitol

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Pope Francis addresses the U.S. Congress in the House Chamber on Capitol Hill in Washington, D.C., September 24 2015.

Pope Francis at U.S. Capitol

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Mark Perez wears a button bearing the image of Pope Francis while waiting for him to arrive for a visit to Catholic Charities of the Archdiocese of Washington in D.C., September 24, 2015.

Pope Francis at U.S. Capitol

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Pope Francis addresses a joint meeting of the U.S. Congress in the House Chamber of the U.S. Capitol on September 24, 2015 in Washington, D.C.

Pope Francis at U.S. Capitol

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People watch Pope Francis address a Joint Session of Congress in front of the U.S. Capitol in Washington, D.C on September 24, 2015 on the third day of his six-day visit to the U.S.

Pope Francis at U.S. Capitol

JONATHAN ERNST /REUTERS

Pope Francis arrives in the House Chamber prior to addressing a joint meeting of the U.S. Congress on Capitol Hill in Washington September 24, 2015.

Pope Francis at U.S. Capitol

JONATHAN ERNST /REUTERS

Pope Francis (L) is greeted by U.S. Vice President Joe Biden as the pope arrives in the House Chamber prior to addressing a joint meeting of the U.S. Congress on Capitol Hill in Washington, D.C., September 24, 2015.

Pope Francis at U.S. Capitol

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Pope Francis (C) is applauded as he arrives to give his speech to the U.S. Congress in Washington, D.C., September 24, 2015.

Pope Francis at U.S. Capitol

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People pack the West Lawn of the U.S. Capitol to see Pope Francis appear on the Speaker's balcony before his speech to the U.S. Congress in Washington, September 24 2015.