307
The Typical American Lives Only 18 Miles From Mom
(lemmy.world)
Edit: source with some more info
https://www.nytimes.com/interactive/2015/12/24/upshot/24up-family.html
If you assume the number of people who live across the country from their mother is the same number of people who live with their mother, the balance is completely in favor of the across country people. the difference between 0 and 18 is way less than the difference between 18 and 1200.
This was explained in a different comment.
https://lemmy.world/comment/12558121