In 1764, when the Spanish took over New Orleans, the Creoles needed work, which led to many of them becoming traveling musicians. These musicians were the inventors of early jazz, through their expression of African dancing and music. On Sundays, they would gather on a grassy plain on the northwestern edge of the city, where slaves were allowed to dance. This area became known as the Congo Square because of the use of African cultural elements and dances.
Gangs, known as Mardi Gras Indians, roamed the streets on Mardi Gras day during the early 1880s. They wore masks to disguise themselves as Native American Indians because they felt a spiritual kinship with them. To taunt one another, the gangs would use drums and chants that were similar to the West African and Caribbean music. The processions were viewed by future jazz figures Louis Armstrong and Lee Collins who, according to National Park Service, remember being affected by their influence.
In the late 1880s, brass marching bands became very popular when they combined syncopated piano compositions along with influences of African-American musical styles. This ragtime style got its name from the improvisation of music to a livelier tune for dancing. "Papa" Jack Laine's Reliance Brass Bands were among the best-known racially integrated bands. It was the leader in the first generation of white ragtime bands, or white jazzmen, as they were also known.
Funerals and parades added community participation, known as the second line, to join in the dancing processions. According to National Park Services' Jazz History, once a funeral had ended, those present to mourn the dead would instead celebrate the life of the person they had lost with music and dancing. The community participants in the parades became known as "the second line" -- second to the official society members and hired band. This practice has continued through the years and can still be seen in New Orleans.
PBS.org states that jazz was greatly influenced by two similar, yet morally different styles of music. Gospel, which praised God, and the blues, which consisted of songs of praying to what's human. Though churchgoers frowned on blues music, the beats were interchangeable. It was the content that differentiated these two styles, but together they were the start of jazz music to come.
The jazz style changed at the turn of the century with the softening of the brass sound by using string instruments like the violin or guitar. With this, musicians began to improvise their sound, especially those who could not read sheet music. Charles "Buddy" Bolden took an improvised blues and mixed it with a faster-paced, familiar dance tune. This gave Bolden a unique sound that separated him from the traditional jazz style.
In the early 1900s, jazz began to travel through America. Mississippi riverboats helped to spread "Dixieland Jazz," as it was known, through dance excursions that also provided employment for jazz musicians. This style featured collective improvisation, in which all the musicians would do their solos at the same time.
Louis Armstrong was the leading figure for solo improvisation when he left New Orleans to go to Chicago after Joe "King" Oliver requested his presence. Armstrong would play his solos during breaks in the music, a style that allowed musicians to have individual solos as opposed to the Dixieland style. This trend soon became the norm among jazz musicians.
During the Great Depression, jazz shifted to swing. The composer Jelly Roll Morton added a sophistication to the solo musicians that gave structure to the new swing era of the 1920s. New Orleans musicians had to adjust through the 1930s and 1940s with swing, causing the jazz sounds to drift away from the original music. A national revival movement was stimulated by Bunk Jonson and George Lewis in the late 1930s, taking jazz back to the small-band style of New Orleans.