For starters:
1. A huge stock bubble hedged at cents on the dollar, that dried up liquidity when it burst.
2. A post war Europe that was bankrupt.
3. High tariffs.
4. Poor money management by the treasury which led to deflation.
5. Coinciding natural disasters that decimated the economy of entire regions of the country (read dust bowl).
6. A massive influx of cheap labor that left put natural downward pressure on wages, that grew on itself once unemployment hit 10%.
Food production wouldn't stop for awhile, but shipment would.
No. Trucks would run, trains would switch at site for a while and the snail mail would carry bills and payments, just like the old day.
Electrical grids may come back on line, but what are you going to plug into them when everything with a circut board is fried.
First, an EMP from a 10 kiloton class weapon isn't going to do that kind of damage beyond the immediate area, maybe 20 miles. Let's say its over NYC. Everything of vital importance to the economy is backed up off site on a near real time basis. We'd shut down the NYSE for a few days and then continue. Chances are the secondary markets would already be in heavy action on those stocks by the that time.
A massive emp attack would look exactly like what was feared about Y2K. If you don't understand what that kind of instantaneous reversion to a preindustrial society would do to our civilization, I don't know what to say to you.
You could throw all of the computer boards in the ocean tomorrow and we would not revert to a preindustrial society. Sorry, but my hysteria threshold is too high to buy into your doomsday scenario.
Now if they created an EMP over Russia that led to Pooty Poot launching ICBMs our way, we'd suffer grievous damage.
Apparently the Heritage Foundation and a blue ribbon commission that had the unfortunate luck to publish their finding on the same day as the 911 commission disagree with you.