Tatum also extended jazz piano's vocabulary and boundaries far beyond his initial stride influences, and established new ground through innovative use of reharmonization, voicing, and bitonality.

Tatum grew up in Toledo, Ohio, where he began playing piano professionally and had his own radio program, rebroadcast nationwide, while still in his teens.

He left Toledo in 1932 and had residencies as a solo pianist at clubs in major urban centers including New York, Chicago, and Los Angeles.

[22] In an interview as an adult, Tatum denied the story that his playing ability developed because he had attempted to reproduce piano roll recordings that, without his knowing, had been made by two performers.

[35] He frequently played for hours on end into the dawn; his radio show was scheduled for noon, allowing him time to rest before evening performances.

[37] As word of Tatum spread, national performers passing through Toledo, including Duke Ellington and Fletcher Henderson, visited clubs where he was playing.

[39] Although Tatum was encouraged by comments from these and other established musicians, he felt that he was not yet, in the late 1920s, musically ready to move to New York City, the center of the jazz world and home to many of the pianists he had listened to growing up.

[40] This had changed by the time that vocalist Adelaide Hall, touring the United States with two pianists, heard Tatum play in Toledo in 1932 and recruited him:[41] he took the opportunity to go to New York as part of her band.

[44] After his arrival in New York, Tatum participated in a cutting contest at Morgan's bar in Harlem with the established stride piano masters – Johnson, Waller, and Willie "The Lion" Smith.

[64] This lifestyle contributed to the effects of the diabetes that Tatum probably developed as an adult, but, as highlighted by his biographer, James Lester, Tatum would have faced a conflict if he wanted to address his diabetes: "concessions – drastically less beer, a controlled diet, more rest – would have taken away exactly the things that mattered most to him, and would have removed him from the night-life that he seemed to love more than almost anything (afternoon baseball or football games would probably come next)".

[69] Thus, in 1937 he left Los Angeles for another residence at the Three Deuces in Chicago, and then went on to the Famous Door club in New York,[69] where he opened for Louis Prima.

[76] The overseas trip appeared to have boosted his reputation, particularly with the white public, and he was able to have club residencies of at least several weeks at a time in New York over the following few years, sometimes with stipulations that no food or drink be served while he was playing.

[87] They were a commercial success on 52nd Street, attracting more customers than any other musician, with the possible exception of vocalist Billie Holiday, and they also appeared briefly on film, in an episode of The March of Time.

[89] Nevertheless, Tatum was awarded Esquire magazine's prize for pianists in its 1944 critics' poll, which led to his playing alongside other winners at the Metropolitan Opera House in New York.

[96] The Billboard reviewer commented, "Tatum is given a broken-down instrument, some bad lights and nothing else", and observed that he was almost inaudible beyond the front seating because of the audience noise.

[93] A fellow pianist from the years after World War II estimated that Tatum routinely drank two quarts (1.9 L) of whiskey and a case of beer over the course of 24 hours.

[108] Although Tatum remained an admired figure, his popularity waned in the mid-to-late 1940s, likely due in large part to the advent of bebop,[109] a musical style he did not embrace.

[112] In the same year, Tatum toured the U.S. with fellow pianists Erroll Garner, Pete Johnson, and Meade Lux Lewis, for concerts billed as "Piano Parade".

[121][122] The trio did not play with Kenton's orchestra on the tour,[122] but had the same performance schedule, meaning Tatum sometimes traveled long distances by overnight train while the others stayed in a hotel and took a morning flight.

[150] Composer and historian Gunther Schuller describes "a night-weary, sleepy, slurry voice, of lost love and sexual innuendos which would have shocked (and repelled) those 'fans' who admired Tatum for his musical discipline and 'classical' [piano] propriety".

[153] Over time, he added to his repertoire – by the late 1940s, most of the new pieces were medium-tempo ballads but also included compositions that presented him with harmonic challenges, such as the simplicity of "Caravan" and complexity of "Have You Met Miss Jones?

[155] Tatum was able to transform the styles of preceding jazz piano through virtuosity: where other pianists had employed repetitive rhythmic patterns and relatively simple decoration, he created "harmonic sweeps of colour [and] unpredictable and ever-changing shifts of rhythm".

The melodic lines may be transformed into fresh shapes with only a note or a beat or a phrase particle retained to associate the new with the original, yet the melody remains, if only in the listener's imagination.

[150] Beginning in the 1940s, he progressively lengthened the runs to eight or more bars, sometimes continuing them across the natural eight-bar boundaries of a composition's structure, and began to use a harder, more aggressive attack.

[165] Schuller argues that Tatum was still developing toward the end of his life – he had greater rhythmic flexibility when playing at a given tempo, more behind-the-beat swing, more diverse forms of expression, and he employed far fewer musical quotations than earlier in his career.

[166] Critic Whitney Balliett wrote of Tatum's style, "his strange, multiplied chords, still largely unmatched by his followers, his laying on of two and three and four melodic levels at once [...] was orchestral and even symphonic.

[109][172] This increased his playing's impact,[172] as did his seemingly effortless technique, as pianist Hank Jones observed:[24] the apparently horizontal gliding of his hands across the keys stunned his contemporaries.

[181] Even musicians who played in very different styles, such as Bud Powell, Lennie Tristano, and Herbie Hancock, memorized and recreated some of his recordings to learn from them.

[180] He made jazz musicians more aware of harmonic possibilities by changing the chords he used with great frequency; this helped lay the foundations for the emergence of bebop in the 1940s.

[190] Others, including trumpeter Rex Stewart and pianists Oscar Peterson and Bobby Short, were overwhelmed and began to question their own abilities.