After I transcribed the sheet music, I found that this song was in the Digital Tradition, although the "negro dialect" was cleaned up. Anyhow, since I did the work, here's my transcription:

Oh! Dat Low Bridge!
(Edward Harrigan & David Braham)

It's many miles to Buffalo - Oh, dat low bridge!
Balky mule he travel slow - Oh, dat low bridge!
Dar's gravel on de tow path, Dar's hornets in de sand,
Oh, pity poor canallers, Dat's far away from land.

CHORUS
Den look out dat low bridge, Look out dat low bridge,
De captain, cook, and all de crew, Oh, duck your head way down,
The fastest boat in all de fleet,
Two sisters come to town.
(dance)


Dar's many locks to shut you in - Oh, dat low bridge!
Every worm must learn to swim - Oh, dat low bridge!
We're loaded down with barley, and lumber from de west,
Oh, every poor canaller, Now do your level best.

CHORUS

We're froze up in the winter time - Oh, dat low bridge!
Summer how de sun do shine - Oh, dat low bridge!
In rain or stormy weather, De captain's on de poop,
All huddle up together, Like chickens in de coop.

CHORUS

Dar's groceries in de cabin dar - Oh, dat low bridge!
Never leaks, she's full of tar - Oh, dat low bridge!
Dar's freckles on de children, Dar's glanders on de mule,
Mosquitoes by de million, Who keep de golden rule.

CHORUS


(Words by Edward Harrigan, Music by David Braham)
As sung in Edward Harrigan's new comedy, The Grip
copyright 1885, by Wm. A. Pond & Co.

Source: American Memory Collection, Library of Congress