According to "The Life ans Legend Of Leadbelly" by Charles Wolfe and Kip Lornell, (page 18):

"Most of the parties and dances ... were held in rural houses miles from the nearest town and often miles from the nearest white homestead. 'They call them sukey jumps,' Huddie recollected many years later. Sukey or sookie was apparently a Deep South slang term dating from the 1820's and referring to a servant or slave. A sukey jump, therefore, was once a dance or party in slave quarters. Huddie himself once explained the term by saying, 'Because they dance so fast, the music was so fast, and the people had to jump, so they called them sooky (sic) jumps.' Sookie, Huddie thought, was derived from the field term for a cow, and was used to call a cow. Whatever the case, These late nineteenth century country dances gave Leadbelly the first public platform for his music."

Another source to go to is "Mules And Men" by Zora Neale Hurston, who knew Leadbelly in New York; she describes them as being dances around big bonfires.

Hope this helps.

Lyle