President Jimmy Carter visited Nigeria and Liberia in 1978.

As a former president, Carter has made many trips to Africa, focusing on diseases, such as river blindness and malaria. The Carter Center’s campaign to eliminate Guinea worm disease is hailed as a major success.

Another former president, Bill Clinton, used his foundation to sponsor humanitarian projects in Africa.

“So you can actually, immediately and directly see the results of your initiatives in Africa. That is more difficult in other parts of the world,” said Professor Lichtman.

Health care experts say George W. Bush’s initiative to fight HIV and AIDS in Africa has saved millions of lives. Since leaving office, Bush and his wife Laura have remained active in African health issues.

Helping people in Africa resonates in a positive way at home.

“It is not only the presidents, it is the U.S. public and U.S. Congress, I think, that sees itself as doing those kinds of things in the world - a moral force for good,” said Cooke.

And that is a legacy many leaders seek.