Economies fall, water and food moved to to Urban areas,. Harsh summers and winters cause rural towns to rise up.
The East Coast and Midwest all lose power within 24 hours leaving Millions hurting. Old US Government struggles, New North American Government formed out of Canada, Mexico, and rest of old USA that has Power.
The Old USA that has 20 States as Members presses on and invests time and recourses into the Nation Guard turning Inward. The World has Eyes on all the recourses of the East Coast and Mississippi coast line.
Towns and Cities turn into Settlement Zones. Federal Government is very Small only worrying about defense and power and water
Many Other Counties have fallen apart having civil wars and turned into City State lead Governments