I never gave EMP much thought until reading the book, One Second After.
http://www.onesecondafter.com/
In a Norman Rockwell town in North Carolina, where residents rarely lock homes, retired army colonel John Matherson teaches college, raises two daughters, and grieves the loss of his wife to cancer. When phones die and cars inexplicably stall, Grandma’s pre-computerized Edsel takes readers to a stunning scene on the car-littered interstate, on which 500 stranded strangers, some with guns, awaken John’s New Jersey street-smart instincts to get the family home and load the shotgun. Next morning, some townspeople realize that an electromagnetic pulse weapon has destroyed America’s power grid, and they proceed to set survival priorities. John’s list includes insulin for his type-one diabetic 12-year-old, candy bars, and sacks of ice. Deaths start with heart attacks and eventually escalate alarmingly. Food becomes scarce, and societal breakdown proceeds with inevitable violence; towns burn, and ex-servicemen recall “Korea in ’51” as military action by unlikely people becomes the norm in Forstchen’s sad, riveting cautionary tale, the premise of which Newt Gingrich’s foreword says is completely possible. —Whitney Scott
Although it's a bit dated, Alas Babylon! is also well worth a read.