America's best-loved historian died of natural causes today. Mr. McCullough made his name with The Johnstown Flood in 1968. The book was a bid deal in western Pennsylvania. McCullough was one of us, from the area. He won Pulitzer Prizes for Truman and John Adams. The undersigned has read those three plus Mornings on Horseback, a biography of Theodore Roosevelt. David McCullough was 89.