Boeing has been providing planes for US Presidents for decades now, as we already know. The tradition was started by President Eisenhower back in 1959, when he became the first President to climb aboard a jet plane.
Eisenhower's plane was a Boeing 707 Stratoliner. He must have really enjoyed the experience, because since then, every subsequent President of the United States has been loyal to Boeing. As the company is already working on the next version of Air Force One, the relationship will continue into the future.