My dad was a Physicist, and we had couple of long talks about this before he passed. In truth, no one knows exactly how badly an EMP event over North America would hurt our electronic infrastructure. My own educated guess is it would be devastating, in ways we may not even suspect.
The 1962 Starfish Prime airburst was over the Pacific, 900 miles from Hawaii. Nonetheless, Hawaii was hit pretty hard. In Oahu, hundreds of street lights failed, TV's and radios were screwed up, alarms were triggered and several power lines were fused together. 3 LEO (low earth orbit) satellites were instantly destroyed, and the resulting band of radiation eventually killed or disabled 1/3 of the LEO satellites that were exposed to it.
This was a BIG deal in the scientific community at the time. That year, my dad had taken a sabbatical from teaching at CU and was a senior staff scientist at Ball, working on a contract to build 3 of the first 10 satellites America ever put in space. Many Physicists were saying at the time that if we had conducted that airburst over the Nevada test site (where many bombs were tested!) we would have wiped out the electrical infrastructure of the Western United States and probably destroyed our economy!
Keep in mind that all this happened at a time when the transistor was a novelty and the integrated circuit was not yet in use.
The Soviet Union conducted sub-orbital nuclear tests of their own at about the same time (way out over the 'stans) and they had similar experiences with power lines conducting the pulse hundreds of miles back from the test site and starting fires in power plants at the other end of the line.
Long story short, we scared the sh*t out of ourselves and each other.
There are several concerns. 1) The magnetic field over North America is stronger than the field over the Pacific, which would magnify the pulse. 2) Millions of transistors are printed closer and closer together in each new generation of integrated circuit, making them more and more vulnerable. 3) Computers/integrated circuits are everywhere, used to control virtually everything. 4) EMP effects have been simulated in testing, but due to budget constraints they stopped increasing the intensity of the pulse without finding out at what point widespread destruction occurs in various kind of electronic equipment, and 5) The US government is complacent as hell about EMP for civilian infrastructure, but serious a hell about it for their own purposes.
I find number 5 to be the most ominous of all.
Also (and this is only peripherally related to EMP) I was dismayed to learn that the US has fallen far behind other countries in sheltering our population in a conventional nuclear war. Russia is said to be able to shelter 40% of their civilians. Switzerland can shelter 100%! America can shelter only a portion of the elites, who look at the rest of us as if we were aphids.
This is one of several reasons why I have a strong preference for the old mechanically injected Cummins diesel engine, although durability, simplicity and fuel efficiency rank higher.
While we're on the topic, I'd lose the tinfoil hat right away. Copper is a much better conductor!
