Dancing starts at 0:58
edited excerpt from http://blogs.loc.gov/folklife/2014/08/buffalo-gals/:
The origin of “Buffalo Gals” is often given as having been composed by the minstrel show performer John Hodges under his stage name “Cool White” in 1844. It is an early example of a song sung by a white man who performed in black face using a mock African American dialect. Just one year later another white group who performed in black face, The Ethiopian Serenaders, published sheet music for “Philadelphia Gals,” (1845) with similar lyrics and no attribution for a composer or lyricist.
Minstrel singers often changed the name of the song to reflect the name of the town where they performed, in order to appeal to local audiences. In 1848, The Ethiopian Serenaders published another version, “Buffalo Gals” (presumably for Buffalo, New York), also unattributed. This is the first sheet music version of the song as it is most familiar to us today.
Fiddle players in parts of Virginia and West Virginia call this tune “Round Town Gals,” “Round Town Girls,” or “Midnight Serenade.” In 1987 Chris Goertzen and Alan Jabbour published an article that traced the tune to an 1839 publication of dance tunes, Virginia Reels, Selected and Arranged for the Piano Forte, by G.P. Knauff with the title “Midnight Serenade,” providing evidence that the melody existed as a dance tune in this region before the minstrel show song versions were published.
As Goertzen and Jabbour pointed out in their article, the titles “Round Town Gals” and “Midnight Serenade” suggest the possibility that calling girls to come out and dance may be the point of the tune as it is in the song “Buffalo Gals,” and that there may have been similar lyrics that preceded minstrel show versions as well.
Was there a song or a dance call that asked “Round town gals won’t you come out tonight and dance by the light of the moon?” Who are those buffalo gals? The bison is a symbol of America, especially the American west. As the song takes on new life, the “gals” may be women of the west, pioneers, cowgirls, or perhaps fancy women.