This mail was carried on a train that run between Greenville and Columbia S.C.. That line is no longer in use. Also I don't think the Bookman post office exists any more.
It appears this card was postmarked on a railroad train because it has rms in the killer bars. From the text on the card the people most likely placed the card in the mail in LA, CA and the card was to be delivered to family in Independence, Kansas. Why is it post marked Denver Colo Air Mail Field? Was the card placed on a air plane in Denver to complete its journey to Independence or did it continue on rail to Independence?
I have been collecting postcards for a long time. I am going to post some of them here for your enjoyment and pleasure. Feel free to comment and send me any information you may know about the cards.