A new episode of Research Rabbit Hole, our Facebook Live show, premiered Monday evening, May 3, at 9 p.m. ET.

Season 1, Episode 9, is focused on backdrops, one of the great clues to help trace the photographers who used them—and, with a little grit, determination, and luck, maybe identifying the unknown face looking back at you. But where did photographers get those backdrops? We’ll shed some light on this question.

The full season is available on YouTube.

New episodes of Research Rabbit Hole premier every two weeks on our Facebook page. The host, Ronald S. Coddington, is Editor and Publisher of Military Images.