Pope Francis heads for US and a deeply divided Washington

Pope Francis headed for Washington today for the first visit of his life to the United States, bringing his "church of the poor" to the world's wealthiest superpower and a country polarized over issues closest to his heart: immigration, social injustice and economic inequality.

President Barack Obama planned to greet Francis on the tarmac at Andrews Air Force Base upon his arrival from Cuba, according a rare honor to the pontiff. Presidents usually make important visitors come to them at the White House.

During his six-day, three-city visit to the U.S., the pope will meet with Obama, address Congress, speak at the United Nations in New York and take part in a Vatican-sponsored conference on the family in Philadelphia.

The 78-year-old Argentine known as the "slum pope" for ministering to the downtrodden in his native Buenos Aires is expected to urge America to take better care of the environment and the poor and return to its founding ideals of religious liberty and open arms toward immigrants.

Francis' enormous popularity, propensity for wading into crowds and insistence on using an open-sided Jeep rather than a bulletproof popemobile have complicated things for U.S. law enforcement, which has mounted one of the biggest security operations in American history to keep him safe.

The measures are unprecedented for a papal trip and could make it nearly impossible for many ordinary Americans to get anywhere close to Francis. For anyone hoping to get across town when the pope is around, good luck.