Instruments were often improvised, with guitar & mandolins being made from the necks of discarded guitars fastened to large gourds. The gourds were flattened on one side, with a sound-hole cut into the flat side, before drying. Banjos were sometimes made from a discarded guitar-neck and a metal pie-plate. The eponymic jug was just that, a jug played by buzzing across the neck, used as a bass instrument, with some degree of pitch change controlled by the lips, but often played as a drone.
Early jug bands were typically made up of African American vaudeville musicians who found themselves unable to find work as entertainers after vaudeville died. They resorted to playing a mixture of Memphis blues (even before it was formally called the blues), ragtime, and Appalachian music on street corners for tips.
It has been said that "The history of jug bands is the story of the birth of the blues". W.C. Handy said that he learned blues style from street musicians, playing improvised instruments. The informal and energetic music of the jug bands also contributed to the development of rock and roll.
Jug bands were a popular and widespread form of musical entertainment until supplanted by big bands and swing in the 1930s.
Perhaps the best known traditional jug band was Gus Cannon's Jug Stompers, whose song "Walk Right In" was a hit in the 1920s and 1930s and was reprised by folk musicians in the 1960s. Among modern jug bands, Jim Kweskin's Jug Band was the most successful. The Even Dozen Jug Band was also well known.
Modern tributes to the jug band include "Willie and the Poor Boys" by Creedence Clearwater Revival and "Jug Band Music" by the Lovin' Spoonful. John Sebastian of the Lovin' Spoonful currently leads the J-Band, that includes not only musicians from the modern folk revival, but Yank Rachell, jug band leader from the original era.