In 1938, as Seneca was emerging from the Great Depression, construction of a new post office signaled improving conditions. The Colonial Revival building became especially notable for its lobby mural, "Men and Wheat," painted in 1940 under a New Deal arts program by Joe Jones, a struggling 30-year-old Missouri artist. The mural depicts a Nemaha County farm scene with a tractor and combine harvesting wheat. After its installation, Seneca's International Harvester dealer objected that the green equipment looked like advertising for rival John Deere, so Jones repainted the combine Harvester Red and placed his own name as a logo on the green tractor. Today, Joe Jones's works are held in major art museums across the nation and at the White House in Washington, D.C., and the Seneca Post Office mural is listed on the National Register of Historic Places.