If ragtime piano can be seen as the starting point in the evolution of jazz piano, then the next step in that evolutionary process wasn't a step all; it was a "stride." Around 1920, the popularity of ragtime piano began to wane, as blues music became the new fad. In response to this — while also incorporating some of the influence of Tin Pan Alley — several pianists, primarily in Harlem, began to experiment with a blending of styles. The result was stride piano. Thomas Wright "Fats" Waller was an American jazz pianist, organist, composer, violinist, singer, and comedic entertainer. His innovations in the Harlem stride style laid much of the basis for modern jazz piano. SOURCE: Wikipedia. The Joint Is Jumpin' was released in 1937. Words by Andy Razaf and J. C. Johnson, music by Thomas "Fats" Waller/arr. Alan Billingsley. From the 1978 musical Ain't Misbehavin'. The musical is a tribute to the music of Fats Waller. It was a time when Manhattan nightclubs such as the Cotton Club and the Savoy Ballroom were the playgrounds of high society and Lenox Avenue dives were filled with piano players banging out the new beat known as swing.