Set to Hershy Kay’s rollicking arrangements of folk melodies, George Balanchine’s Western Symphony (1954) gallops onto the stage with gunslinging bravado, fusing the elegance of classical ballet with the rowdy charm of the American frontier. The stage is transformed into an Old West complete with cowboys and saloon girls performing whirlwind pirouettes and high kicks while exhibiting plenty of playful swagger. With its sweeping choreography and showmanship, Western Symphony is both a love letter to Americana and a dazzling showcase of Balanchine’s genius. It’s the finale of a program that begins with two other works from the 1950s, a fantastically productive decade for Mr. B: Square Dance, which sets quadrilles and reels to Baroque music, and the experimental Episodes. —Bill Keenan