Photos: Popes' meetings with US presidents 1959: In this Dec. 6, 1959, file photo, President Dwight D. Eisenhower walks with Pope John XXIII at the Vatican. (AP Photo/Paul Schutzer, File)
Photos: Popes' meetings with US presidents 1963: In this July 2, 1963, file photo, President John F. Kennedy and Pope Paul VI talk at the Vatican. Kennedy's meeting with Pope Paul VI at the Vatican was historic: The first Roman Catholic president of the United States was seeing the Roman Catholic pontiff only days after his coronation. (AP Photo, File)
Photos: Popes' meetings with US presidents 1979: In this Oct. 6, 1979, file photo, President Jimmy Carter, right, talks with Pope John Paul II at the White House in Washington. (AP Photo, File)
Photos: Popes' meetings with US presidents 1965: In this Oct. 4, 1965, file photo, Pope Paul VI, left, and President Lyndon B. Johnson are seen during the Pontiff's visit to New York. The trip presented protocol problems. Johnson wanted to see him, but the pontiff was a chief of a state not officially recognized by the U.S. The solution: Johnson flew to New York for dinner at the apartment of his friend Arthur Goldberg, the U.S. ambassador to the United Nations, and the pontiff was welcomed to Johnson's suite at the Waldorf-Astoria Hotel the next day. (AP Photo, File)
Photos: Popes' meetings with US presidents 1970: In this Sept. 28, 1970, file photo, President Richard Nixon talks with Pope Paul VI as they meet in the Vatican. (AP Photo, File)
Photos: Popes' meetings with US presidents 1982: In this June 7, 1982, file photo, President Ronald Reagan and his wife, first lady Nancy Reagan, meet Pope John Paul II at the Vatican. (AP Photo, File)
Photos: Popes' meetings with US presidents 1989: In this May 27, 1989, file photo, Pope John Paul II presents first lady Barbara Bush with a Vatican Medal as President George H.W. Bush looks at his medal during a ceremony at the Vatican. (AP Photo/Ron Edmonds)
Photos: Popes' meetings with US presidents 1991: In this Nov. 8, 1991, file photo Pope John Paul II invites U.S. President George Bush, accompanied by his wife, Barbara, to meet members of the clergy gathered in the Vatican's Clementine Hall. The President and the Pope met after the President attended the NATO Summit in Rome. (AP Photo/Denis Paquin, File)
Photos: Popes' meetings with US presidents 1993: In this Aug. 12, 1993, file photo, President Bill Clinton points out people in the crowd to Pope John Paul II as he arrives in Denver, Colo. (AP Photo/Bruno Musconi, File)
Photos: Popes' meetings with US presidents 2008: In this June 13, 2008, file photo, President George W. Bush walks with Pope Benedict XVI to the Lourdes Grotto at the Vatican. (AP Photo/Evan Vucci, File)
Photos: Popes' meetings with US presidents 2009: In this July 10, 2009, file photo, President Barack Obama and first lady Michelle Obama meet with Pope Benedict XVI at the Vatican. (AP Photo/Haraz N. Ghanbari)
Photos: Popes' meetings with US presidents 2014: In this March 27, 2014, file photo, Pope Francis and President Barack Obama smile as they meet at the Vatican. (AP Photo/Gabriel Bouys, Pool, File)
Photos: Popes' meetings with US presidents 2017: In this May 24, 2017, file photo, President Donald Trump stands with Pope Francis during a meeting at the Vatican. (AP Photo/Evan Vucci, Pool, File)
Biden meets with Pope Francis at the Vatican 2021: US President Joe Biden, left, exchanges gifts with Pope Francis as they meet at the Vatican on Friday, Oct. 29, 2021. (Vatican Media via AP)