As they did, New York bands began to get the swing of the music. In March 1919, a group from Coney Island called the Original Memphis Five emerged with a streamlined version of the Original Dixieland Jazz Band’s style. They made hundreds of recordings between 1921 and 1929.

Nineteen-nineteen was also the year that a young cornetist named Louis Armstrong, who had been electrifying patrons of New Orleans saloons and honky-tonks with his distinctive sound, began to set his sights beyond his hometown. Armstrong possessed a rare gift for fusing disparate types of music that moved him — he had command over the passion of blues, excitement of ragtime, and the poignancy of operatic and classical melodies. His was the unnamed music of New Orleans: organic, confident and sincere. Playing on Mississippi riverboats, his horn was heard for the first time outside of New Orleans. Inevitably, young musicians like the trombonist Jack Teagarden and the cornetist Bix Beiderbecke heard Armstrong; within a few years, both of these young men would emerge as jazz originals in their own right.

Armstrong had received much of his early experience working in the band led by trombonist Edward Ory, known as Kid. Ory's contribution to early jazz was in creating one of the most fundamental voices of the jazz band: a style known as “tailgate trombone,” which became the model for most that followed. Ory left New Orleans in August 1919 for California. He soon settled in Oakland, leading a fine jazz band at the Creole Café. In the summer of 1922, Ory’s band would become the first black New Orleans jazz band to make recordings.

Armstrong’s mentor, Joe Oliver, moved to Chicago in 1917. By 1919 he was one of the busiest musicians in town, giving Chicago a taste of the Crescent City’s hot music. In 1922 he sent for Armstrong to join his Creole Jazz Band as the second cornetist. The 1923 King Oliver recordings would spread New Orleans music — some called it “jazz” — throughout the land.

On the very day of the 369th’s parade, 2,900 miles to the west, a struggling dance orchestra leader named Paul Whiteman was recovering from a nervous breakdown. A violinist formerly with the San Francisco Symphony, Whiteman had become fascinated with the sensuous, unpolished sounds he heard from musicians in Barbary Coast saloons. He attempted to notate this strange music, orchestrate it and normalize it. Hiring the best “jazzers” in town, Whiteman formed a dance band to play at the Fairmont Hotel. Taxed by overworked and worry, he collapsed, and soon left music, and San Francisco, behind.

But he didn’t stay gone. Whiteman moved east, in 1920, and drew national attention when he signed a contract with the Victor Talking Machine Company. Striving to “make a lady” of jazz led to his fabulous 1924 concert “An Experiment in Modern Music,” which premiered Gershwin’s “Rhapsody in Blue.” Whiteman became known as the “King of Jazz,” a moniker which — while he never took it literally — served him well. He went on to hire Frank Trumbauer, Beiderbecke and others, a dream team of young jazz musicians. By the mid-1920s, jazz was firmly in place as the reigning American popular music style.