April 11 is Barbershop Quartet Day commemorating the day in 1938 when various interested individuals met in Tulsa, Oklahoma to create the Society for the Preservation and Encouragement of Barbershop Quartet Singing in America (SPEBSQUSA.)

This noble work is carried on today by the Barbershop Harmony Society, which carries on research and preservation, provides online classes, and connects people with interest in close, unaccompanied harmony.