Comic strips and consumer culture, 1890-1945, by Ian Gordon, is now online for free.

Ian is now a friend of mine, but well before I ever met him, I thought that this book, originally published by the Smithsonian and researched while he worked there, was one of the best books about comic strips that I've ever read. I highly recommend it. You should download it in case he changes his mind; I just did even though I own the paperback.