It's been written that the Great Crash was the probable reason why Sweet Adeline did not run longer. Another contributing factor may have been the absence of co-star Irene Franklin for five weeks. Franklin had an attack of appendicitis on Sunday, Feb. 11, 1930. She had an appendectomy the following day. A week or so later she and her husband, Jerry Jarnigan (who was also in the show in a small role and had written the music for one of her songs), went down to Havana for three weeks.
They returned on March 11. On March 12, it was announced in the press that she would rejoin the show on March 17. During Franklin's absence, another popular vaudeville star, Lillian Fitzgerald, played Franklin's role of Lulu Ward, which had been tailored very much to her performance persona. In addition to her husband writing the music for one of her songs, she wrote the lyrics for two of them. The next day, March 13, the press reported that the show would close on March 22. Franklin's return to the show ended up being for only the final week of performances.
It may be that her absence had an effect on the box office. Momentum may have been lost, and there may have been a realization that even her return would not help enough. Still, a run of 234 performances was generally considered a good run for a big musical at this time.
In the fall of 1930, there was a five-month tour starring Helen Morgan and Franklin in their original roles.