The painters were Thomas Anshutz, who I wrote about here, Thomas Hart Benton, whose early career I covered here, and the was photographer Walker Evans, Wikipedia entry here.
The nature of the subject matter is young women with "hard" expressions on their faces. They are surprisingly similar.
The subject is Rebecca H. Whelen, daughter of a Pennsylvania Academy of Fine Arts board member. Anshutz taught there for many years. This is an unusual pose for that time and place: a more tranquil expression would have been expected.
From a panel of Benton's America Today mural, now prominently displayed at New York's Metropolitan Museum of Art. The subject is Elizabeth England, future wife of Charles Pollock, older brother of the more famous painter Jackson Pollock. The Pollock brothers studied under Benton, hence the connection.
From one of Evans' New York street scene photos of the late 1920s.