English: Photograph of mural "Sorting the Mail" by Reginald Marsh at the Ariel Rios Federal Building, Washington, D.C.
Notes:

• Date: 1936; dimensions: 6' 7" x 12' 6".
• Photographed as part of an assignment for the General Services Administration.
• Title, date and keywords from information provided by the photographer.
• Credit line: Photographs in the Carol M. Highsmith Archive, Library of Congress, Prints and Photographs Division.
• Gift; Carol M. Highsmith; 2009; (DLC/PP-2009:083).
• Forms part of: Photographs in the Carol M. Highsmith Archive.

More information at The Living New Deal
Mural information from the General Services Administration:

Like Alfred D. Crimi, whose murals are located on the same floor of the William Jefferson Clinton Federal Building, Marsh chose to depict the activities of the urban mailroom. Also like Crimi, Marsh made on-site preparatory sketches. He studied the railway mail service located under old Penn Station in New York, as well as the New York post office department building, observing the modern machinery, interviewing postal workers, and making sketches as they unloaded and transferred mail cargo. Marsh's depiction differs, though, from the easy interaction between men and machines portrayed in Crimi's mural, as well as the staid calm of the railway mailroom shown in a sketch for an unrealized mural by Regionalist artist Thomas Hart Benton. In contrast to these, Marsh's murals bring to life the frenzied energy of workers and their machines in what the New York Times called a "brilliant orchestration of labyrinthine structural rhythms."
In the mural's lower portion, muscular men lift and drag large bags of mail. Their varied skin tones and apparel indicate a diverse work force, and their physiques convey heroic strength and power. The upper portion of the fresco—rendered in shades of green, black, and white—showcases the machinery that moves the mail in all directions. Marsh's intricate composition and confident technique capture both the mechanization of systems and the importance of workers.