The US is very, very large. Even the largest bombs would wipe out only a single city. In the worst case you'd see little damage beyond 30 miles from the blast, but at 7 miles from the blast you'd see little left standing. Of course the radiation and fallout will damage people further from the blast. I live over 30 miles from my nearest big city (detroit) and so do most americans.
It would terrorize us, and kill hundreds of thousands or millions depending on the target (New york and LA being some of the densest cities in the US) but even our densest cities are fairly sparse by world standards for big cities.
So chances are good that you wouldn't be directly affected by such a blast.