The modern world is dependent on electricity, and the United States is no exception. I remember the notorious blackouts that affected the eastern U.S. and Canada in August 2003. The duration of the mass power outage lasted anywhere between several hours and a week depending on where you were. I was in Hamilton, Canada, and it was chaos.
Hospitals’ ability to perform emergency surgeries depends on their backup power units, and if the blackout had lasted longer than their battery capacity, there would have been actual deaths. Police departments were overburdened with having to manually direct traffic at intersections all over multiple cities. Thousands of retailers and other businesses had to suspend their operations. Subway systems in Toronto and New York City ground to a halt. If the blackout had lasted longer than it did, it would have been a large-scale disaster for both countries.