Former President Joe Biden, who is Catholic, said Pope Francis was "unlike any who came before him," adding that "I am better for having known him."

By the time Francis took over as leader of the Catholic Church in 2013, meetings between the president and the pontiff had become commonplace. During the dozen years that he served as the pontiff, Francis, who died April 21, met each of the three men who served as the U.S. president during his papacy.