Origins
Banjo-like musical instruments are common to all of the world's most ancient cultures, including those originating in Africa, the Middle East and China. Early instruments featured animal skins drawn tight over a tortoise shell or gourd.
The Slave Instrument
The modern banjo developed from native African instruments that were recreated by enslaved black Africans in the early years of the United States. The first such proto-banjos consisted of a piece of animal skin stretched over a hole cut in a calabash gourd and tacked in place, with a round rod serving as the neck. They had three or four strings made of twisted horse hairs, gut, or whatever else could be found to serve the purpose. These instruments were variously called banjars, bangoes, and a few other similar names.
Just how those earliest instruments developed into the modern four-string and five-string banjos that are now familiar is not well documented. The story seems to begin with a man named Joel Sweeney from Virginia. Joel is credited with changing the banjo from an improvised folk instrument into a popular performance instrument, but it's not at all clear which parts of the tale are true and which are myth.
Getting Popular
Joel is said to have learned how to play a four-string gourd banjo along with other entertainment skills from black folk when he was a young teenager. He later donned blackface and became a popular touring minstrel entertainer in the 1830s, playing his home-made five-string banjo, dancing and singing. Where, when and how the fifth string was introduced and whether it was a bass string or a high drone string as in the modern 5-string banjo are not clear. Minstrelry swept the nation, and Sweeney went on to become an international star. He toured the British Isles and may even have played for Queen Victoria, thus introducing the banjo to Great Britain. Before Sweeney, the banjo was unknown to most people and deprecated by those who knew of it only as a folk instrument of the black slaves, people who were at that time regarded as an inferior, crude and ignorant people. Keep in mind that some people of that time also seriously regarded the fiddle as an instrument of the devil himself. In addition to popularizing the banjo, Sweeney taught many others to play, thus creating a foundation for generations of banjoists to come.
Minstrel shows that featured the banjo became extremely popular in the US during the last half of the 19th century. Itinerant minstrel troupes and their banjos rode the great Mississippi riverboats, and the banjo was carried and played by the settlers and Gold Rush prospectors who were pushing into the Wild West.
Becoming a "Real Instrument"
Up to the 1870s or so, banjo necks (the long thin part where the strings are fingered) had no frets and the instruments were played by strumming with the fingernails and thumb in a manner that was derived from the way the African instruments were played. About that time, a new style of playing was developed. In this new style, individual strings were plucked (picked) to sound single notes in a way similar to European guitar techniques. This quickly led to the fretted fingerboard, which allowed players to more accurately finger notes higher on the neck (closer to the body of the banjo). The fretted fingerboard and the finger-picking style of play greatly expanded the musical range of the banjo, and the instrument began to earn some respect as a "real musical instrument." It then became a melody instrument as well as a rhythm instrument. In the last decade of the 19th century, banjo bands were formed of different types of banjos for different harmonic ranges. In addition to the regular banjo, which covered the baritone range, there was a cello banjo for bass, a small piccolo banjo for tenor. The lead was played on a banjeaurine, which had a shorter neck and was tuned a fourth higher that the regular banjo. Playing in a banjo band was considered hip by the socialites of the day. As part of this thrust to legitimize the banjo, bands were even attempting to play classical music. The banjo, however, was just not suitable for that sort of music. By the end of the century, the public's pleasure had turned away from banjo music to embrace the new jazz dance band music, and the banjoists themselves turned more to ragtime music.
Because of the great popularity of the banjo, there were many manufacturers of the instrument by the end of the century, and its construction had changed radically. The original gourd body had been replaced by a circular wooden or metal rim, and metal strings and a metal tone ring had been introduced. (See 'Anatomy of a Banjo' under banjo for details.).
Early in the new century, the idea of using a flat pick or plectrum on metal strings gained currency. This trick was borrowed from the mandolinists and grew in use because it produced a louder and brighter sound than the finger-picked or strummed gut-string banjos. The result was the development of the 4-string tenor banjo and the plectrum banjo, new types of banjos that were more suited for this style of playing. The general popularity of banjo music declined with the coming of the Great Depression, and the masses turned to other new and vigorous music styles. The banjo was relegated to niche genre like Appalachian mountain music, country music and dixieland jazz.
Back in the Limelight
In the late 1950s and early 1960s, the banjo made a comeback that had its roots in musical innovations that occurred in the 1940s and 1950s. One innovation was bluegrass music and the other was the use of folk music as a tool of social reform.
Bluegrass was a distinctive new type of music born of country music and mountain music, and was launched largely by band leader Bill Monroe, who associated the term bluegrass with this music, and banjoist Earl Scruggs in the 1940s. The addition of Scrugg's novel three-finger picking style to the Bluegrass style that Monroe had been developing opened a new dimension for this kind of music by allowing the banjo to relieve the fiddle in lead parts,. Bluegrass quickly grew in popularity within the country circuit, but it was later brought into the national consciousness when two of Scruggs songs made it into the Billboard Top 10 singles list. What made Bluegrass a household word, however, was a TV show, The Beverly Hillbillies. Scruggs wrote and played the theme song, "The Ballad of Jed Clampett", which was played on national TV every week and hit a number one on Billboard. Another boost was the soundtrack for the hit 1967 movie, "Bonnie and Clyde", also done by Scruggs and his band. The frenetic "Foggy Mountain Breakdown", which was the theme for the movie, became known to just about everyone. Another highly popular banjo movie theme was "Dueling Banjos" from Deliverance, in which a banjo and folk guitar battled it out in a melody war.
Banjoist Pete Seeger was a leader of the folk music for social change movement in the 1940s (His book, How to Play the 5-string Banjo, is still a big seller.) Pete and his banjo were deeply involved in the civil rights and anti-war movements of the 1960s, and the folk music genre was very important to both social movements. On the head of his banjo was inscribed, "This machine surrounds hate and forces it to surrender." The image of Pete Seeger with his banjo was often seen in the mass media, and became an icon for peaceful social protest. The banjo was also featured in the music of pop/folk groups like The Kingston Trio and The Brothers Four, groups that followed a pattern set by Pete Seeger and the Weavers.
Another, although musically minor, phenomenon of the 1960s and 1970s that raised awareness of the banjo was the nationwide chain of Shakey's Pizza Parlors, which featured live performances of 'old time' banjo music played by banjoists in blazers and flat-top straw hats back then.
That all resulted in a great surge of popular interest in banjos, in the 1970s and the demand for the instrument became so great that many companies sprung up to manufacture bluegrass banjos. That wave has since passed and those companies are now gone. The banjo and its music have not completely left us, however. It is being kept alive by innovative young players like Bela Fleck.