Well, phisically, the answer is easy: there's a chance some of us are breathing the molecules that once were on his body, or have ate'em in a form of a fruit or something similar.
Spiritually, the answer is more complex. He could be ( and that's not the only options)
01 - In heaven
02 - In one of the multiple heavens/planets of afterlife
03 - Sleeping waiting the judgement
04 - In purgatory
05 - In Hell
06 - Reincarnated somewhere (we can rule out Washington from this "somewhere

)
07 - Free from the circle of Reincarnations
08 - Free from the circle of Reincarnations on this plane of existence
09 - Reborn
10 - gone, ceased to exist
11 - a part of God
... ok, what I forget?