Richard Nixon

A university student came up with the idea in 1956, which came to fruition four years later. At the time, Fred Kahn didn't know that his idea would change the face of presidential politics in America.

Nixon was the first sitting president to resign from office, while Biden is the first sitting president in two generations to pull out of a presidential race. Both men are part of American history

In the midst of the Watergate scandal back home, Nixon needed a distraction. After years of isolation, his trip to Damascus on 15 June 1974 paved the way for future visits by US presidents.