Depends on where. When I lived in GA suburbs, it was about 50/50.
After that, I moved to a few large cities on both coasts(and been to plenty others), and I don't remember visiting more than one or two households where wearing shoes inside was ok. The only exception to this was when someone was hosting a large houseparty, in which case wearing shoes inside was expected about half the time (you wouldn't want your feet to make contact with whatever could be on the floor at some of those, such as occasionally spilled liquor).
After that, I moved to a few large cities on both coasts(and been to plenty others), and I don't remember visiting more than one or two households where wearing shoes inside was ok. The only exception to this was when someone was hosting a large houseparty, in which case wearing shoes inside was expected about half the time (you wouldn't want your feet to make contact with whatever could be on the floor at some of those, such as occasionally spilled liquor).