English: 'The Family Industry and Agriculture' mural in the Ambler, Pennsylvania Post Office artist- Harry Sternberg. Sternberg and his family are the main figures in the painting. The painting was made for the U.S. Treasury's Section for Painting and Sculpture and is thus public domain. It is also public domain because it was published in 1939 without a copyright mark. Note that the photographer on Flickr has licensed it as CC BY-NC-SA 2.0, but since it is already public domain that license has no force.