I Got Rhythm · Jazz Wiki

“I Got Rhythm” is a 1930 George and Ira Gershwin show tune that quietly became the second-most important chord progression in jazz, after the blues. Strip away Ira’s lyric and Ethel Merman’s belt, and what’s left is a fast, cyclical harmonic skeleton — nicknamed “rhythm changes” — that generations of bebop composers wrote brand-new melodies over. This note is about that skeleton: how the A section moves, how the bridge moves, and why so many other famous heads are secretly this tune wearing a different hat.

The A section: a turnaround stretched into a whole phrase

Gershwin’s refrain is built almost entirely out of one shape jazz players already know by heart — the I–vi–ii–V turnaround — except here it isn’t a two-bar tag, it’s the entire 8-bar A section. In B♭, the first four bars state the cycle twice, compressed to two chords a bar:

B♭6 – G7 | C-7 – F7 | B♭6 – G7 | C-7 – F7

Bars 5–6 break the pattern to tonicize the IV chord: B♭7 acts as a secondary dominant (V7/IV) landing on E♭7, and a diminished passing chord (E°7) walks the bass chromatically back up toward B♭, before the last two bars snap back to the same I–vi–ii–V turnaround to close the phrase:

B♭7 | E♭7 – E°7 | B♭6 – G7 | C-7 – F7

That’s it — one 8-bar idea, repeated verbatim as the second A. Because the harmony moves in two-chord bars and never sits still, it’s a genuinely different technical problem from a ballad like Autumn Leaves: you don’t have time to think, you have to hear the cycle coming.

The bridge: the “Sears Roebuck” dominant chain

The bridge throws out the I–vi–ii–V logic entirely and replaces it with four dominant 7th chords, each a fourth apart, two bars each — a textbook chain of backcycled dominants where every chord is the V7 of the next one rather than resolving “properly”:

D7 | D7 | G7 | G7 | C7 | C7 | F7 | F7

That’s III7–VI7–II7–V7 in Roman numerals, a descending circle-of-fifths slide (D→G→C→F) that keeps deferring resolution until F7 finally lands back on B♭ at the top of the last A. Because none of these dominants is diatonic to B♭ except the last, the bridge is really four brief detonations of tonicization, one per key area, gone before your ear settles — which is exactly why it’s such a good workout for hearing substitutions like tritone subs layered on top later on.

Full form and why it’s a rite of passage

Form: AABA, 8+8+8+8 = 32 bars (the 1930 sheet music is actually 34 bars with a 2-bar tag, but jazz players universally trim it to the clean 32).
Key: most often B♭ on the bandstand, though the original show key was D♭.

Rhythm changes earned its status as the standard blowing vehicle second only to the 12-bar blues because it’s fast, harmonically generic, and completely detachable from Gershwin’s melody. Bebop composers in the 1940s wanted tunes that moved quickly at up-tempo, showed off technique, and — not incidentally — could be copyrighted as new compositions since the underlying chords weren’t protectable. Rhythm changes gave them a form everyone in the room already knew cold, which meant no rehearsal was needed to call it at a jam session, only the letter of a new head.

The contrafact family

A contrafact is a new melody composed over an existing tune’s changes — not an arrangement or a cover, a different piece entirely that happens to share harmony. Rhythm changes spawned one of the largest such families in the American songbook:

“Cotton Tail” — Duke Ellington (1940)
“Lester Leaps In” — Lester Young (1939)
“Anthropology” and “Thrivin’ on a Riff” — Charlie Parker & Dizzy Gillespie (1945–46)
“Moose the Mooche” — Charlie Parker (1946)
“Salt Peanuts” — Dizzy Gillespie
“Oleo” — Sonny Rollins (1954)
“Rhythm-a-ning” — Thelonious Monk (1957)

Each of these keeps the B♭6–G7–C-7–F7 cycle and the D7–G7–C7–F7 bridge intact while replacing the pentatonic Gershwin tune with something more angular, syncopated, and specific to the composer’s own bebop vocabulary — proof that in jazz, the changes and the melody are two separable inventions.

♫ Listen

Don Byas & Slam Stewart — “I Got Rhythm” (Town Hall, New York, June 9, 1945): tenor and bass alone, no rhythm section — the cleanest possible exposure of the tune’s harmonic skeleton, with Stewart bowing and singing his solo in octave unison.
Miles Davis Quintet with Sonny Rollins — “Oleo” (Bags’ Groove, 1954): the contrafact’s debut recording, with the head played over walking bass while the piano lays out, so the A-section turnaround and the bridge cycle are audible straight from the bass line.
Charlie Parker & Dizzy Gillespie — “Anthropology” (1945–46): a fast bebop contrafact that shows how a far more virtuosic melody can sit on the exact same I–vi–ii–V cycle and dominant bridge.