No one description of jazz adequately outlines this ever changing music; no definition can pinpoint simply when and where it all began, nor even settle when the name "jazz" took hold over variants like "jass" or "Jasz."  The spelling of the word took years to stabilize.  Jazz represents a multiformity of musical ideas and originating influences.

African American music forms of slave culture and the black American experience were already shaping this emerging musical idiom (and others) for probably a hundred years.  Music of rent and house parties, after work dances, religious song, cries of street vendors, work songs, and field hollers, blues, jug bands, and juking were some of the places and art forms created within African American communities.

Even before the composed rags of Joplin, Turpin, Scott, and Lamb, in the early 1900s, there had existed for nearly two decades "shout piano" or "jig piano."  Piano ragging was an improvisational reworking the tempos of known tunes played by ear.  Ragging style was applied by the popular virtuoso banjo players, in minstrel show music, in string bands, and for buck dancing.  Later, the immense distribution of parlor uprights and player pianos throughout the country allowed ragtime to be easily incorporated into the repertoires of music reading players at home as well as in clubs.

Jazz's New Orleans roots represent just one stage of growth; it did not simply spring forth as the entertainment of the professional parlors of the Storyville district of New Orleans.  The new jazz bore the stamp of Caribbean, Spanish, French, and South American ideas.  Although most of the jazz innovators and emulated masters of early jazz were African American, jazz's musical core also incorporates Western European ideas.  New Orleans at the turn of the century was home to many music organizations; there were frequent ragtime balls and an availability of brass instruments.  Numerous New Orleans Creoles and former slaves were classically trained as well as being accomplished pianists, kept busy by the high level of musical activity.

Missouri played no small role in developing jazz forms.  St. Louis was a major stopping off point for musicians headed to New York and Chicago from New Orleans in the 1910s and 1920s.  Kansas City was on the western edge of the TOBA circuit (Theater Owners Booking Agency, provided bookings for black performers).  It was a major stop for the traveling musicians on a circuit already established by earlier minstrel shows, carnivals, and vaudeville acts where mainstay blues performers such as Ma Rainey, Mamie Smith, and Bessie Smith performed for the mainstream.  Kansas City also became home to musicians when tours disbanded which brought no less a contributor than Count Basie to Kansas City when his band broke up.

Publishing in Sedalia ushered in the smashing success of Scott Joplin's "The Maple Leaf Rag" in 1899, selling a million copies, a first in the publishing industry, and the mutually supportive relationships between entertainers, businessmen, and city officials created the so called "wide open" cities.  This generated a context of ample work for musicians in Sedalia when it was a major railhead, and Kansas City, during the Pendergast regime.  Work meant, then as now, in any genre, being exposed to outside musical ideas, other artists, and having ample occasion to invent and develop performance and stylistic ideas.

Jazz was immensely popular as dance music (until the 1940s when bop came in) and in rural areas, bands regularly played at road houses, dance clubs, movie theaters, juke joints, and vaudeville stops.  Bands nurtured enthusiasm for dance and influenced other genres while the bands themselves developed regional styles.  The jazz that flourished in Kansas City in the 1930s was so influential it came to be known as Kansas City style.  This style swept the nation because of its swing, upbeat danceable drive, and strong sense of rhythm around which riffs were improvised.  St. Louis hosted the development of key blues and rhythm and blues players.

Leadership still emanates from these cities.  In St. Louis, the formation in 1968 of The Black Musicians Group (BAG) created a nucleus of musicians devoted to fostering the creativity and livelihoods of not strictly bop musicians by assisting with promotion, concerts, and recording.  Kansas City has a Jazz Commission as part of city government.  Both cities have jazz and blues organizations and host outstanding jazz and blues festivals and concerts throughout the year.

Source page - http://www.coin.missouri.edu/
community/folkarts/jazz.html