Empire / Orson Scott Card.

Enhanced descriptions from Syndetics:

The American Empire has grown too fast, and the fault lines at home are stressed to the breaking point. The war of words between Right and Left has collapsed into a shooting war, though most people just want to be left alone.

The battle rages between the high-technology weapons on one side, and militia foot-soldiers on the other, devastating the cities, and overrunning the countryside. But the vast majority, who only want the killing to stop and the nation to return to more peaceful days, have technology, weapons and strategic geniuses of their own.

When the American dream shatters into violence, who can hold the people and the government together? And which side will you be on?

Orson Scott Card is a master storyteller, who has earned millions of fans and reams of praise for his previous science fiction and fantasy novels. Now he steps a little closer to the present day with this chilling look at a near future scenario of a new American Civil War.