ACCRA, Ghana -- The first African-American president came to the continent of his father to exhort Africans on Saturday to rid themselves of corruption, embrace democracy and move from the grand, often violent, struggles of liberation and tribalism to the quieter, more potent movement of stability and economic growth.

In a half-hour speech described as a major foreign policy address, U.S. President Barack Obama stood before Ghana's boisterous parliament, with a backdrop of festive kente cloth and adoring crowds cheering outside....