Hollers is a "whole 'nother subject," as someone said, and needs another thread. The 1901 date for first documented observation is wrong (Adele Thomson, in Richie, above).
A field holler was noted by Frederick Law Olmstead in 1853 ("The Cotton Kingdom"), as he saw a loading gang of Negroes making a fire. "Suddenly one raised a sound as I never heard before: a long, loud musical shout, rising and falling and breaking into falsetto, his voice ringing through the woods in the clear, frosty night air, like a bugle-call." They were rolling cotton bales up an embankment.

One of the first recorded dates to 1851, and does concern the river boats and the rousters. It also was used by Negro firemen loading a fire engine:

Fire on the quarter-deck, Fire on the bow,
Fire on the gun-deck,
Fire down below.
(last line sung or shouted by all hands)
"Every-Day Commerce," in Schwaab., ed., Travels II.

Both of the above from Dena J. Epstein, "Sinful Tunes and Spirituals, 1977, Univ. Illinois Press.

Courtlander, "Negro Folk Music," published a number of them