1. EMP – one nuclear bomb, detonated high in the ionosphere, can ruin your whole decade. Most of the U.S. could be without power for a very long time.
Computers and anything using computer components would be burned out. It’s hard to say just how extensive the damage would be. Most cars would probably be inoperable. Cell phones may or may not be burned out, but the cell towers definitely would be dead. Radio, TV, cable, internet, would all shut down for a very long time. The infrastructure that supports modern communications took many decades to build up, and it would take just as long to rebuild.
Once we lose power, communications, and most transportation, there’s no way to grow food but by manual labor. I’m not sure if irrigation systems would work. But the commercial system which provides seed, fertilizer, and other resources would collapse. Money would probably be next to worthless, and most businesses would be instantly bankrupt. The end result of all this chaos would be famine.
2. Fuel Shortage – Remember the gasoline shortages of the 1970′s? OPEC placed an oil embargo on the U.S. due to our support for Israel in the Yom Kippur war. Prices went way up, and supply went way down. Well, there are lots of other ways that an oil and gas shortage could occur. War in the Middle East would do it. Or some political dispute leading to another embargo. Another trigger for a fuel shortage could be economics. If one of the major oil companies had an economic meltdown, similar to the banking crisis a few years back, the production and distribution of oil and gasoline could be disrupted.