The worst effect is not on what is naturally shielded, or intentionally shielded. The problem is that the long lines of the electrical grid, both transmission and distribution are pretty much perfect antennae for the various EMP pulses.
Modern cars, well grounded appliances and the natural shielding of commercial structures might indeed save electronics.
But the electric grid will go down. Without electricity USA society will collapse in three to nine days. It will take longer to get even portions of the grid back up.
I have lost the link but a British economist/ sociologist wrote a great paper that was essentially “ 9 days from the Middle Ages “. It covers how society collapses rapidly and why.
So as you read about EMP bear in mind the real danger is that you and your family would have 3-9 days before you live in a 12th century, pre-industrial age that shifts rapidly from event to realization to chaos to barbarism/feudalism. How long recovery and reorganization takes is a worthy debate.
90%+ population loss is the general prediction target, mostly and rapidly in urban population areas. “No city can feed itself” is an axiom. Neither can it water or fuel itself.
Two worthy titles are indeed ‘One second after’ and the movie Remnants.
Net: if the grid goes down you have <72 hours to get to a place out of urban areas. After 48 hours travel will be dangerous and lethal after 72. 9 days to have everything to survive for 90 days, then perseverance and perspiration to go on til reorganization and recovery take hold.