I had a chance to look at a Reminisce Magazine yesterday. If you haven't seen this magazine you should check it out. This magazine has everything from postcards, advertisements, photos and such about the United States from the 1920s to the 1950s.You can check them out at their website and even subscribe to their free newsletter.
What struck me was that in the back there was a reader's section and some of the readers had written in and were sharing photographs, looking for descendants of those pictured.
Just goes to show you that genealogy and your ancestor's stuff is out there. It's just a matter of finding it!