Pope Francis Turns Attention to US as Cuba Trip Winds Down

— -- The pope’s historic visit to the United States is hours away.

Pope Francis is scheduled to arrive in Washington, D.C., this afternoon after wrapping up his trip to Cuba. His final stop on the island is in Santiago, with a Mass at the country’s most-revered shrine and a pep talk with families.

Francis' address to families and symbolically potent flight to the United States underscore two of the big themes of his Cuba pilgrimage: encouraging reconciliation within families and between the United States and Cuba. He worked behind the scenes as mediator in 18 months of secret talks on re-establishing diplomatic relations between the two nations.

On his arrival in Cuba, the pope described the success of the negotiations as an example of peacemaking for the entire world. The Vatican spokesman said Monday night this trip was aimed partly at encouraging progress in the continuing effort to normalize U.S.-Cuba ties in fields ranging from commerce to environmental cooperation.

The end of Monday was marked a by a classic Pope Francis moment. Instead of traveling in a limousine or private car, the pope traveled by minibus to the seminary where he spent the night.

The pope also lit a candle and offered flowers at the Virgin of Charity in the town of Cobre Monday.

Before his flight to Santiago, Francis celebrated Mass in Holguin, a city of about 300,000 in eastern Cuba. In his homily, he pressed some of the subtle themes he has developed during this balancing act of a Cuban visit. He told the crowd the biblical story of how Jesus picked a lowly and despised tax collector, Matthew, and instructed him without casting judgment to follow him. That act of mercy changed Matthew forever.

Francis told the Cubans that they, too, should allow themselves "to slowly overcome our preconceptions and our reluctance to think that others, much less ourselves, can change."

"Do you believe it is possible that a tax collector can be a servant?" he asked on Day 3 of his visit to the island. "Do you believe it is possible that a traitor can become a friend?"

It was a theme Francis sketched out Sunday night in an off-the-cuff encounter with young people. He encouraged them to dream big about what their life could be like, and not be "boxed in" by ideologies or preconceptions about others.

"If you are different than me, why don't we talk?" Francis asked the crowd. "Why do we always throw rocks at that which separates us?"

Pope Francis is slated to arrive in Washington, D.C., at 4 p.m. ET today.

A White House welcoming ceremony and meeting with President Obama are scheduled for Wednesday, along with other events in the nation’s capital, before he travels to New York City and Philadelphia.

The Associated Press contributed to this report.

Get real-time updates as this story unfolds. To start, just "star" this story in ABC News' phone app. Download ABC News for iPhone here or ABC News for Android here. To be notified about our live weekend digital reports, tap here.