After the end, the world will be un-American. This speculation forms the nucleus of Un-American Dreams, a study of US apocalyptic science fiction and the cultural politics of disimagined community in the short century of American superpower, 1945–2001. Between the atomic attacks on Hiroshima and Nagasaki, which helped to transform the United States into a superpower and initiated the Cold War, and the terrorist attacks on the World Trade Center and the Pentagon, which spelled the Cold War’s second death and inaugurated the War on Terror, apocalyptic science fiction returned again and again to the scene of America’s negation. During the American Century, to imagine yourself as American and as a participant in a shared national culture meant disimagining the most powerful nation on the planet. Un-American Dreams illuminates how George R. Stewart, Philip K. Dick, George A. Romero, Octavia Butler, and Roland Emmerich represented the impossibility of reforming American society and used figures of the end of the world as speculative pretexts to imagine the utopian possibilities of an un-American world. The American Century was simultaneously a closure of the path to utopia and an escape route into apocalyptic science fiction, the underground into which figures of an alternative future could be smuggled.