He told regional leaders Wednesday that “Africa has been left behind for much too long. But not anymore. Africa is the future.”

In his last announced trip abroad as president, Mr. Biden relished touring a U.S.-financed train line in Angola intended to transport goods and critical minerals to port.

Joe Biden pledged lasting U.S. engagement with Africa as he met his Angolan counterpart Joao Lourenco in Luanda on Tuesday, as part of his first and only visit to sub-Saharan Africa as U.S. president.