What role did the trombone play in a New Orleans jazz ensemble?

In a traditional New Orleans jazz ensemble, the trombone played a vital role within the polyphonic collective, where each instrument was assigned a specific function to create independent yet harmonically linked lines.1

The trombone’s primary responsibility was to provide contrapuntal asides in the tenor or baritone range. This style of playing is often associated with the term "tailgate," which originated from the custom of seating trombonists at the rear of trucks during parades; the style is characterized by the frequent use of slides to transition between long, sustained tones.12

By the period between 1910 and 1915, this systematization of instrumental roles allowed the ensemble to function as a cohesive unit, with the cornet stating the melody, the clarinet performing obbligato or descant lines in a high register, and the rhythm section providing a harmonic foundation.1