American Cardinals Joseph Tobin and Raymond Burke could be candidates to lead the Catholic Church after the death of Pope Francis.

Pope Francis held strong relations with the United States throughout his papacy, and his visit to Washington in 2015 was historic. (AP Video: Mike Pesoli)

For six days in September, 2015, Pope Francis made a historic visit to the United States, visiting some of the country's biggest cities and speaking to massive crowds of the faithful along the way.

Pope Francis, whose time as head of the Catholic Church was noted for humility and outreach efforts to people of disparate backgrounds and faiths, has died at 88, the Vatican said. The pontiff's funeral is scheduled for Saturday,

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.