alternatehistory.com

There's a couple of ways. Either he's shot by the initial bullet, but the headshot misses; he's shot and paralyzed and he'll be in a wheel chair for the remainder of his years; someone else gets the killing shot (Jackie, for example); he avoids getting shot altogether in Dallas; or he avoids going to Dallas. Or other. Each choice would affect the timeline in an understandable way.
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