The mural Achelous and Hercules (1947) was commissioned in 1946 for display at the Harzfeld’s department store in Kansas City. For the mural, Benton chose a theme from Greek mythology, the story of Achelous and Hercules, which he found in Bulfinch’s Mythology – a book that recounted classical myths and stories from different eras. The myth explains the origins of agriculture: Achelous, the river God took the form of an angry bull during flood season and traveled the earth tearing new channels with his horns. Hercules defeated Achelous by tearing off one his horns, and then the horn transformed into nature’s cornucopia – a symbol of abundance and nourishment in classical antiquity. The myth explains how the development of agriculture depends on the taming of rivers that overflow their banks and destroy croplands.

In the mural, Benton reimagined the Greek myth in the setting of the American Midwest. Hercules is depicted as a midwestern cowboy, and the fruit and vegetables spilling from the cornucopia are products that farmers grow in the area. The mural is populated with figures that represent the rural midwestern community. To distinguish this from a simple midwestern farm scene, Benton adds the allegorical figure of Victory sitting on the cornucopia: she is offering a laurel lead and holding a fluttering red drape. Through the story of Achelous and Hercules, Benton addressed both regional and national issues. For Benton, the myth was relevant to the local environment and the Army Corps of Engineers' efforts to control the Missouri River. The artist wrote: “The story is thus applicable to our own land. It's our Missouri River, which yet needs the attention of a Hercules”. The mural celebrates the abundance and richness of the Midwest and American agriculture. This was a timely subject, as it coincided with the Marshall Plan, the initiative of President Henry Truman that provided aid and economic assistance to countries in Western Europe, helping to rebuild their economies after World War II.

Benton reinterpreted the myth in a way that reflected contemporary American life. In a way, the mural was also symbolic of the artist’s professional situation. Benton painted the mural at a time when he was alienated from the East Coast art scene: he was labeled by critics as a loud, gawky, and provincial artist. In the mural, Benton rebuffs his critics: he promotes his figurative style, emphasizing his bold use of color and the vitality of his athletic figures. Achelous and Hercules stands in contrast with the art that was developing in New York in the 1940s. The dominant trend of the decade was Abstract Expressionism, an artistic movement promoted by Mark Rothko, Adolph Gottlieb, and Benton’s former student Jackson Pollock. Benton’s mural not only celebrates the abundance of midwestern agriculture, but also the richness of midwestern art.

In 1947 Achelous and Hercules was hung in Harzfeld’s department store in Kansas City. It was purchased by the Smithsonian American Art Museum in 1985 and is now exhibited on the 2nd floor of the North Wing of the Museum.