President Barack Obama had his first audience with Pope Francis Thursday at the Vatican. The visit is seen as an attempt to strengthen the relationship between the White House and the Catholic Church. President Obama and Pope Francis are expected to speak about shared causes, such as income inequality, but also delve into their disagreements on abortion, contraception and same-sex marriage.

With his visit to Vatican City, Mr. Obama continues the tradition of presidential meetings with the pope that began with the 28th president of the United States.

Here is a history of U.S. presidential visits to the Vatican:

• Woodrow Wilson was the first U.S. president to visit the pope at the Vatican. President Wilson met with Pope Benedict XV on Jan. 4, 1919. Wilson was first in Paris to negotiate the treaty to end World War I, when he decided to travel to Rome.
• President Dwight D. Eisenhower visited Pope John XXIII at the Vatican on Dec. 6, 1959. Eisenhower was the first American president in 40 years to visit a reigning pope. His visit started a tradition that continued with each of his successors.
• In July of 1963, President John F. Kennedy made one trip to the Vatican during his presidency to meet with Pope Paul VI. Kennedy remains the only Roman Catholic American president thus far.
• President Lyndon Johnson made one trip to the Vatican during his time in office on Dec. 23, 1967. Johnson met with Pope Paul VI.
• President Richard Nixon visited the Vatican twice. Pope Paul VI received Nixon in March of 1969 and September of 1970.
• President Gerald Ford was the last American president to visit Pope Paul VI at the Vatican, on June 3, 1975.
• President Jimmy Carter was the first American president that Pope John Paul II received at the Vatican in June of 1980.
• President Ronald Reagan traveled to the Vatican twice during his two terms in office. Reagan met with Pope John Paul II on June 7, 1982 and June 6, 1987.
• President George H. W. Bush also visited Pope John Paul II at the Vatican on two occasions. The pope received President Bush in May of 1989 and November of 1991.
• President Bill Clinton met with Pope John Paul II on June 2, 1994, at the Vatican. The Clinton administration and the Vatican openly clashed on issues such as abortion and war.
• President George W. Bush traveled to the Vatican more than any other American president. John Paul II first received President Bush on May 28, 2002. In June of 2004, Bush presented Pope John Paul II with the Presidential Medal of Freedom at the Vatican. It was the last time Pope John Paul II would receive an American president before his death in 2005. President Bush also visited Pope Benedict XVI while in office, both in June 2007 and June 2008.
• President Barack Obama visited with a reigning pope once before during his time in office. Obama met with Pope Benedict XVI on July 10, 2009, at the Vatican.

The pope has also met with the presidents several times in the United States:

• On Oct. 4, 1965, Pope Paul VI met with President Johnson in New York City. Pope Paul VI was the first reigning pope to visit the United States.
• Presidents George W. Bush and Jimmy Carter are the only American presidents to receive a pope at the White House. Pope John Paul II came to Washington on Oct. 6, 1979, and Pope Benedict XVI visited the Bush White House in April of 2008.
• On May 2, 1984, President Ronald Reagan met with Pope John Paul II in Fairbanks, Alaska. The pope was on his way to South Korea, as President Reagan was returning home after a trip to China.
• President Reagan and Pope John Paul II also came together on Sept. 10, 1987 in Miami, Fla. During a joint address for World Youth Day, President Bill Clinton and Pope John Paul II spoke to thousands of students on Aug. 12, 1993 in Denver, Colo.