Jimmy Carter, the 39th president of the United States, has lived long enough to overlap with 17 other commanders-in-chief.

On the occasion of former President Jimmy Carter turning 100 on October 1, President Biden honors Carter’s decades of public service and humanitarian work, as well as his hopeful vision of our country and tireless commitment to a better world. https://t.co/jxAhEYqs0T pic.twitter.com/Ke6B29t2Gv

Back in 1976, Carter changed the way presidential candidates are nominated and elected. He went on to provide models of what to do – and what not to do.