The Cummington Story was a production of the U.S. Office of War Information, a government agency World War II that operated from 1942-1945. The propoganda short was shot as a silent film with narration and a score by Aaron Copland. While he never made a suite from the film score, he later used some of the themes and material in the piano solo In Evening Air.
"The same or similar music" to In Evening Air had earlier appeared in the 1944 piano work Midday Thoughts, in the documentary film score The Cummington Story, and in the Clarinet Concerto, writes biographer Howard Pollack (Aaron Copland: The Life and Work of an Uncommon Man, p.515). The piece shares its title with a 1964 poem by Theodore Roethke, the last two lines of which are printed at the end of the score (Pollack p.410).