I debated for a while about whether or not to transcribe this tune. At first glance, I assumed that it belonged with the "Lagniappe" tailgating tunes on the album since it lacks a prominent trombone melody and features improvisation through most of its duration. However, because the trombone is the solo active horn part in the form, "Dumaine St." is actually a jam on a basic melody.
The trombone solo is based entirely on the Eb blues scale. Its range covers about an octave and a half. There are not any trademark Shorty riffs or techniques. While it is not a simple solo, most of its phrases can be easily learned in all twelve keys as a woodshedding exercise.
After sitting down and analyzing this tune, it made me wonder if "Dumaine St." could be an outtake from the Backatown album. It is in the same key as the eponymous tune, although, honestly, it is not as flashy. Perhaps by polishing up the leftover tracks from his previous album, Trombone Shorty is able to produce a new, yet subpar, album in quickly manner.
Lastly, try overlaying some of the "Backatown" licks on top of the "Dumaine St." jam. What do the kids-these-days call this... a mashup?
And speaking of the kids-these-days, NPR featured Trombone Shorty as part of its Tiny Desk Concert series. But in keeping with spirit of "Dumaine St.," here is a YouTube video [explicit] of a second line parade on Dumaine St. That's right... a parade of second-liners.
Recommended Reading: Gates of Eden by Ethan Coen. Published by Dell Publishing.