Right now 20th century photography geeks are experiencing something of a perfect storm. From a new coffee table book, to a major museum exhibition, to images just made available on Wikimedia Commons — these photo collections reveal long hidden corners of American urban social and cultural history.

First up: Vivian Maier. We wrote about her earlier this year when her pictures were exhibited for the first time in Chicago. Maier had an eye for odd juxtapositions and magical moments as she captured strangers in the city. A fraction — albeit a truly excellent fraction — of the 100,000 negatives in the Maier trove were selected for a book published by powerHouse Books this month. Maier died before the recent discovery of her work, and her biography is still a bit hazy. Once you dig into the little that is known about her, you'll find yourself searching for more clues in her arresting self-portrait on the cover.

Arthur Leipzig, Chalk Games, Prospect Place, Brooklyn, 1950. (The Jewish Museum)

New York's Photo League (1935-1951) was a collective of photographers who believed the medium could be an agent for social change. For 15 years its members shot the everyday: a shoe shine boy, teenagers at a dancing school, kids playing chalk games in the street. This month the Jewish Museum in New York mounts a survey exhibition about the League. And don't miss the radio story on the exhibit by WNYC's Sara Fishko, who spoke with four of the surviving members of the League.

More amazing Depression-era photos surfaced online last month when the Smithsonian's Archive of American Art posted around 200 of its the Federal Art Project (FAP) photos to Wikimedia Commons. The FAP documented the activities of the Works Progress Administration, a New Deal agency created to employ people in public works projects, including many artists. Some taught art, others painted murals in government buildings, and some designed posters for the National Parks.  Given our current state of unemployment, it's hard not to be nostalgic for this great era of government supported public art projects. 

Slideshow: 20th Century Photography