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This book reminded me of "House of the Scorpion" by Nancy Farmer, "The Giver" by Lois Lowry, and "Uglies" by Scott Westerfeld. If you like those, you'll like this.

It's about a girl who lives in the U.S. (that's "Unified States") years after the Line was set up to keep people in and out. A bomb was dropped during a war that the U.S. really was the bad guy in, though the textbooks and "official" stories have all been changed (sound familiar?), and the radiation caused them to seal off the U.S. from part of itself, now called "Away". So Rachel is curious about the Line and Away and the Others (the people living in Away) and her mother has a past as a revolutionary and is hiding from the government, which has turned in to an attacker of its people rather than a protector of its people.

So it's a fast read, young adult novel, but I sense there are more to come.