https://www.randomhouse.com/knopf/authors/caro/desktopnew.html
Every time a youth from a poor family gets to go to college because of one of Lyndon Johnson's Great Society programs, and thus to escape from a life in the ghetto, and every time a black man or woman is able to walk into a voting booth and cast a vote because of one of Lyndon Johnson's Voting Rights Acts, that is a more significant example of political power. And so, unfortunately, is the fact of a young man dying a needless death in a useless war in Vietnam. In order to demonstrate and illuminate political power through a biography of a single individual, the biography has to be of the right individual. I selected Robert Moses because in The Power Broker what I was aiming at was to show how urban political power worked in America in the middle of the twentieth century--how power worked not just in New York, but in all our great cities; to show what was the true essence of urban political power, not the trappings but the heart, the raw, naked essence of such power. I selected Moses because he was never elected to anything. But for forty-four years he exercised more power in New York City and New York State than any official who was elected--more than any mayor, more than any governor. Therefore, I felt, if I could show what Moses' power consisted of, and how he got it and how he wielded it, I would be showing the true essence of urban political power. Since no one else ever wielded such power, Moses was the ideal subject.