Love that time period of American history, so there's no shortage of possible topics. Here are a couple that spring to mind:
The 1920s drug problem - Opium dens proliferated in the late 1800s early 1900s, but our first real heroin addiction problem took place in the late 1920s, on a much smaller scale than today's problems, of course, so it sometimes gets overlooked. During Prohibition a fair number of people abused drugs instead of alcohol (or in addition).
WPA Music, Theater and Art - A smaller, lesser known part of the Works Progress Administration subsidized artists, actors and musicians to produce murals, works of art, plays and musical shows. They were often at a local level and represented really the first time the government provided funding for the arts. Sort of a forerunner to the Nationa Endowment for the Arts.
The Expatriates - I know less about this topic, but what if your research included the "Paths of the Expatriates" to Paris especially, what happened in each of their lives to motivate them towards that Mecca of discontent, as it were.