Boswell was a favorite duet partner of Bing Crosby, and they frequently sang together on radio as well as recording several hit records as a duo in the 1930s and 1940s. (Crosby and The Boswell Sisters first sang together in 1931 on a 12" medley of songs from the then-current George White's Scandals, issued on Brunswick 20102.) She and Crosby recorded a version of "Alexander's Ragtime Band" which was introduced by Eddie Cantor that was a No. 1 hit in 1938. This recording benefited the National Foundation for Infantile Paralysis, which later became the March of Dimes. In 1939, Crosby and Boswell had three hit duet records that each climbed into the top 12 on Billboard; "An Apple for the Teacher" climbed all the way to No. 2.
