Regarding the ending of all electronic things in the U.S. in one fell swoop:

I studied about this in college from Government research records on hydrogen bomb battle tactics so what I wrote recently is a real thing not fictional in any way. Of course this is theoretically what would happen if you set off a 100 megaton Hydrogen bomb at 100 miles because we don't really know what this would do to the atmosphere. But, because of the proximity to metal in the U.S. of most people they figure about 1/3 of the population would die from EMP lightning from anything metal burning a hole through most people and instantly frying them to death in that moment of the EMP pulse.

this is what I wrote in another Article: Autonomous Robots (land, air, sea, space) need acc...

For example a 100 megaton Hydrogen Bomb set off in the center of the U.S.  at 100 miles above the earth would permanently end any electronic device of any kind that was above 10 feet underground over the whole U.S. in one moment. And anyone within 12 feet of anything metal would die from the Electromagnetic Pulse basically sending a lightning bolt through them from that metal. 

end quote from another article I wrote:

So, the whole point of writing about this recently is finding a way to stop Autonomous Robots from killing everyone say in New York City or Paris or any other large city or military base on earth.

So, I think you are going to eventually see an EMP device as a failsafe for all bigger cities and military bases on earth because of present autonomous robots of the air, Space, lands and seas and under the seas.

So, if you set off an Electromagnetic pulse in a city or military base you would likely also need to have everyone move away from anything metal that can send EMP lightning bolts into them from the EMP.

Another unknown actually is what an EMP of this size would do to the nervous system of every human being simply because human nerves are electrical and low voltage too.

So, a large enough EMP might sterilize everyone or make them pass out temporarily or permanently. So, when you set off an EMP it is likely that some people would die (especially in elevators and in Electrical Vehicles.

Because even after an EMP of any size no car, no truck no EV would ever run again and new technology would have to be brought from another city for anything above 10 feet underground would be fried electrically in that EMP.

However, anything robotic in the vicinity, land, air, water based autonomous robotics would also be fried within the proximity of that city or military base within a certain horizontal and vertical radius(whatever it was) for that generated EMP. 

EMP=Electromagnetic Pulse