U.S. President Barack Obama has returned home from a weeklong trip to Moscow, a G-8 summit, and a stop in Ghana.
Mr. Obama and his family arrived back in the United States shortly after midnight.
On Saturday, the president challenged Africans to take more responsibility for wiping out poverty, war and corruption on the continent.
In a speech to Ghana's parliament, he said good governance is missing from too many places in Africa. He said Africa does not need strongmen, it needs strong institutions.
The emotional high point of the president's visit was a tour of a former slave center from which thousands of Africans once were shipped off to America.
Before leaving Ghana late Saturday, Mr. Obama said he would never forget the image of his daughters, the descendants of Africans and African-Americans, walking through the center's doors of no return, but then walking back out.
Mr. Obama's visit to Ghana was his first trip to sub-Saharan Africa since becoming the first African-American president.
He said it was particularly important for his daughters to see the slave center at Cape Coast Castle and witness how history can take cruel turns.
Mr. Obama said the tour reminded him of a visit to a German World War Two concentration camp. He said both experiences remind him of man's capacity for evil.
The president said several times on his trip to Ghana that Africa is not a world apart, but is a fundamental part of an interconnected world.
He said he chose to visit Ghana because of its "functioning democracy" and its president, John Atta Mills, who Mr. Obama said is "serious about reducing corruption."