CHARLES KELLER (1914-2006) American painter & printmaker, Social Realist & W.P.A. artist, sympathetic to labor and racial equality, well represented in museums such as the British Museum of Art, The Smithsonian, Library of Congress, Schomburg Center and more. A rare and attractive signed lithograph, an early labor portrayal entitled "Concrete Foundations - 6th Avenue Subway" and dated "1939", portraying a black man and a white man working together to mix concrete being poured from a cement truck with other figures working in a dusky atmospheric background, with the words "Brooklyn, NY" visible on truck. Deftly executed in black and white charcoal with dry point etching. Overall size 22 1/2" x 16" with an image area of 17" x 13 3/4". Titled edition ("25 proofs"), date and full signature in pencil beneath image in margin. Condition good with one 2" tape repair at bottom left near title, various creases, faint soiling and toning do not detract significantly, edges rough but sufficiently clear of image area. Keller's devotion to the causes of racial equality and social justice are on full display in the aptly titled "Concrete Foundations". $400-500