Robert Sklar has written a ton of great books on the history of film; any of his titles would serve you well.

_The Genius of the System_ by Thomas Schatz is a very readable history of the Hollywood studio system, during America's Golden Age of film. Mixes comprehensive biographies of all the key producers, directors, and studio heads as well as interesting anecdotes about making films like Casablanca and Gone With the Wind.

Pictures at a Revolution - Mark Harris: an excellent look at the changing Hollywood landscape of the late 1960s through the lens of the five Best Picture nominees from 1968.

Thank you so much!

Adventures in the Screen Trade by William Goldman is more geared toward aspiring screenwriters, but also gives plenty of interesting history of the film industry.

Is That A Gun in Your Pocket? by Rachel Abramowitz. Excellent book.

Aljean Harmetz, THE MAKING OF CASABLANCA: Bogart, Bergman and World War II. Excellent film history, and American cultural history too. (Originally published as "Round Up The Usual Suspects: The Making of Casablanca.")