Perhaps you are familiar with how the Wild West "sounds." The fiddle with foot-stompin' rhythms can be found in the soundtracks of many old Westerns. But how did this sound develop as a key signifier of "Americana"?
Elmer Bernstein (1922-2004), an American film composer, might be credited with making this American Western sound popular in the film world. The soundtrack to The Magnificent Seven (1960) is full of fiddles, percussion instruments that imitate hoof clip-clops, and Mexican-based rhythms and instruments (such as the maracas and Spanish guitar). In fact, he received a Western Heritage Award for his score to that film.
But Elmer Bernstein was the student of Aaron Copland (1900-1990), also an American composer, who produced both film and concert hall repertoire. The Great Depression during the 1930s led to a resurging interest in folk music as a means of reclaiming and creating a unifying American identity that would help the nation through its economic difficulties. Copland's interest in American folk musics led him to meld twentieth-century percussive orchestrations and experimental methods with folk elements. The resulting mixture of sound has since been strongly associated with the American plains and the pioneers of the American West.
Perhaps the several ballets that Copland composed on the theme of the American West also contribute to this association: Billy the Kid, Rodeo, and Appalachian Spring all draw heavily from the white Euro-American folk music tradition. Copland even quotes tunes from cowboy songs: the strains of "Good-bye, Old Paint" can be found in the third movement of Billy the Kid, the section entitled "Mexican Dance and Finale."
For introductory listening to Aaron Copland, try any of the ballets mentioned, or investigate the Grand Canyon Suite, which paints the progression of a full day on the edge of one of the natural wonders of the American West.