Jigs, for the purposes of this post, are tunes in 6/8 time. Think “pineapple apricot, pineapple apricot”. Jigs may have once been part of the Southern repertoire, but by the time the first recordings sprung out of the hills and hollers, 6/8 tunes had all but vanished, except for perhaps a few stalwarts like Irish Washerwoman, Haste to the Wedding and Garry Owen. As a result, today’s oldtime fiddler might know hundreds upon hundreds of 4/4 breakdowns, but only one or two jigs, if any.
According to this interview and demonstration with fiddler and folklorist Alan Jabbour, jigs in the South got converted into 4/4 breakdowns after the Civil War. During the Civil War jigs were used by local militias as marching tunes. The fifers in these militias were often also fiddlers who carried the fife repertoire over to the fiddle. After the South lost the war, these former 6/8 rallying tunes became associated with defeat. So jigs like Bonny Blue Flag and Chapel Hill Serenade were converted into the 4/4 tunes Coleman’s March and Green Willis.
Another theory is that jigs faded out due to the rising popularity of the frailing or clawhammer banjo as an instrument used to second the fiddle. The 6/8 rhythm is not that easy on clawhammer banjo. With no one to play these jigs with, fiddlers may have dropped them over time. These tunes are also used for dances, so if people were no longer dancing in a way that required a 6/8 rhythm, that could also explain the extinction of jigs in the South.
Modern day players of traditional music cannot help but be exposed to lots of different tunes and styles. I know I've heard many jigs at Irish sessions and have enjoyed customizing a personal repertoire that includes both 6/8 tunes and oldtime breakdowns. I hope that other players of oldtime music will take it upon themselves to re-introduce a few 6/8 tunes into their local circles.