The other outstanding non fiction book I read earlier in the year was Only Yesterday by Frederick Lewis Allen.
This is a fascinating social history of America in the 1920's written in 1931, hence the title. There is material here for a plethora of historical crime novels, and I think it would be essential reading for anyone contemplating writing such a book.
The book covers the Red Scare of 1919, the new morality, Teapot Dome, Coolidge prosperity, Lindbergh, Prohibition, Al Capone, the Florida Land boom and of course the Wall Street Crash.
This book shows history does not have to be written many years afterwards, sometimes it can be written more successfully without the intervening events that cloud our view. We know how historical events turned out, but this book written as the depression deepened has an interesting immediacy because the author did not know the end game.
"Here was a new generation.....grown up to find all the Gods dead, all wars fought, all faiths in man shaken." [F. Scott Fitzgerald: This Side of Paradise]