What is the name of Broadway's first "long-run" musical?

The answer is not "The Elves." Broadway's first long-run musical is widely considered to be "The Black Crook." It premiered in 1866 and ran for a record-breaking 474 performances. "The Black Crook" is significant in the history of musical theatre as it combined a melodramatic plot with elaborate dance numbers, becoming the foundation for future Broadway musicals.