NeuromancerRead about the other dystopias on the list.
William Gibson's 1984 novel revolutionized science fiction and popularized the subgenre of cyberpunk. What truly blew readers away was Gibson's vision of a future where governments have crumbled and multinational corporations rule the Earth from orbital mansions. This same worldview was realized in visual form in Ridley Scott's Blade Runner, based on a Philip K. Dick novel, which solidified in many audience's minds the idea that America's future would be a polluted, corporate-controlled urban sprawl.
Why is this an American dystopia?
In the United States, there are less government checks on corporate power than in many other developed nations. Many of our nightmares are fueled by the idea that there will be a runaway power grab by corporations.
Neuromancer made PopCrunch's list of the sixteen best dystopian books of all time and Annalee Newitz's list of "Thirteen Books That Will Change The Way You Look At Robots."
Also see Robert Collins' top ten list of dystopian novels and Gemma Malley's top 10 list of dystopian novels for teenagers.