What Happens to Modern Societies When Electricity Disappears?

Over the summer, I read a moderately terrifying article in the Economist on what would happen if America lost electricity for a long period of time. If, say, hackers managed to infiltrate the system, or North Korea detonated a nuke 40 miles above Nebraska and caused an electromagnetic pulse, or if a solar flare acted up. I'll get to the article's chief worries in a moment. My only experience in an electricity-free realm is trifling and limited to the 2003 blackout of northeastern America....