Richard Matheson's I am Legend has been made into several movies, including the recent Will Smith movie, and The Last Man on Earth, starring Vincent Price. The book itself is set in Los Angeles, CA, in 1976. As the enotes link reference below explains in great detail, though, the year itself is not particularly important--it is post World War II, which is all that really matters. Fears of atomic and biological warfare during the time Matheson wrote the book, as well as the fear of communism making everyone the same, drive the book. Robert Neville, the main character, is one of, if not the only, remaining human being on the Earth. All the rest of the humanoid characters have been changed by some sort of plague to become vampire-like creatures. The book takes place largely in Neville's house, where he barricades himself and conducts experiments on ways either to destroy, or "cure" the vampires. In the book, and in the Vincent Price movie, it finally becomes clear to him that he, Neville, is not only the one who is now different, but that he is feared as a destroyer of the new type of humans that now inhabit the world. I have been told that this was an alternate ending shot for the Will Smith movie, but that audiences preferred the happier, humans-will-continue ending that was used.