[PastorBooks]

“I assume trucks would still somehow roll unless EMP knocks them out as well?”

Assuming the theory behind EMP is correct, most, if not all, trucks would never run again. Engines have too many electrical components to replace.

The only vehicles left running would be 1970s vintage.

[GrandJediMasterYoda]

Wow that is very bad, VERY. No way in hell could food be distributed fast enough to stave off starvation plus I was thinking of all the farming machines, processing plants that would cease to function. Can you imagine the panic and anarchy that would ensue if food production and transportation suddenly ceased? Now I absolutely can see how millions would die, and let me guess: We have zero protection against an EMP attack.

[AndyJackson]

Assuming the theory behind EMP is correct, most, if not all, trucks would never run again. Engines have too many electrical components to replace.

Well the theory is correct, but the theory is not what some folks are claiming the theory is. A megaton class warhead at high altitude would have a huge regional impact. But the impacts are varied depending upon geology, orientation of individual objects, computer placement relative to any structural metal, effects of metal roofs, water absorption.

It's incredibly spotty, and the effect would be way less than 100%.

And, if someone detonates a megaton class warhead over the US, they will be transformed into a sheet of glass with a counterstrike launched before their launch hits us.

[Svartalfiar]

“I assume trucks would still somehow roll unless EMP knocks them out as well?”

Assuming the theory behind EMP is correct, most, if not all, trucks would never run again. Engines have too many electrical components to replace.

The only vehicles left running would be 1970s vintage.

There would likely be a LOT of vehicles still running. An EMP high enough to affect the entirety of North America, coast-to-coast, is going to be much weaker by the time the wave reaches the ground. So much less will be affected.

Also, much of the metal in vehicles acts as a Faraday cage, so many of the components will likely be protected enough. Cars and planes hit by lightning or downed power lines, do little to no damage, yet that's a strong pulse of EM power.

An EMP works by inducing so much current that it burns up and damages electrical components. Depending on strength of the wave and how well-built the components are, and EMP isn't an automatic death sentence for electronics, or every electric component would kill each other, every radio tower, speed gun, red light car sensor, cell phone, and so on would be killing every other electronic device.