“All I Want for Christmas Is You” deftly repackages a number of ’60s harmonic devices to create perhaps the best holiday song of the past few decades. Here’s how those harmonic devices help make the song tick.
After a brief intro of tinkling bells, the song begins with three straightforward chords (in the key of G) and one very strange one.
The first three chords are simply I, I in first inversion, and IV, but the Ao7/Eb chord is tricky. Aurally, it feels like C minor, which would make it a iv chord borrowed from the key of G minor. But if we listen closely to the first verse, there’s clearly an A in the chord, which makes it an Ao7. (It sounds more like a Cm chord in subsequent verses.) That’s still a borrowed chord — Ao7 is iio7 in G minor. However we want to look at it, this chord creates a tension that’s resolved with the return to G major at the start of the next line, which is also the beginning of the chorus.
The B7 on “own” is a V7/vi, pointing our ears in the direction of the E minor chord that arrives at the beginning of the next line. The Cm chord that follows is interesting — it’s a borrowed chord, a iv from the key of G minor. The B7 and Cm chords allow Carey’s twisting vocal to end each of the two lines on the same pitch — or, well, on enharmonic equivalents. I’ve labeled “own” below as a D# because it’s part of the B7 chord and “know” an Eb because it’s part of the Cm chord, but they’re the same pitch on the piano.
The chorus isn’t yet done making left turns. (Or at least the choruses after the first one aren’t — the first omits the last few chords for Carey to sing a cappella, so let’s skip ahead to the second half of the chorus, at 1:25, to continue our analysis.) The next line contains another clever use of a secondary dominant. This time it’s a V7/ii — that is, an E7 that points at A minor.
The chord progression in these two lines makes perfect sense, although the pitches in Carey’s vocal line add harmonic complexity. Here’s what she sings.
In particular, the C in m. 2 and the Eb in m. 4 stand out. The C is a point of emphasis in m. 2 even though it seems to clash with the E7 chord that underpins it. (I think it should be labeled an E7 — it’s hard to tell from the recording exactly how the chord is voiced, but the E in the bass clearly seems to be the root and the note D features prominently in the accompaniment.) The C in the vocal part sounds fine in context, but once you know what it is, it’s hard to ignore it. The passage would likely have sounded a bit smoother had Carey just moved the second bar down a step, from C-D-C to B-C-B. By featuring the C so prominently, though, she creates a tension even greater than the tension dominant seventh chords usually possess, almost turning the chord into a C augmented triad in first inversion (E, G#, C) but with an added B.
The Eb in m. 4 also adds tension to what might otherwise have been a normal dominant seventh chord. Again, there’s an obvious alternative to this note — Carey could have simply sung a D instead, and it would have sounded fine. Instead, the Eb she selected effectively creates an extended chord (D7b9) that increases the harmonic complexity of the passage.
There’s a lot going on here, so perhaps it’s not surprising that the instrumental interlude following the second chorus features a straightforward I / vi / ii / V progression. Pop songwriters will frequently follow passages of tricky, complex harmony with passages that are harmonically simpler, giving the listener’s ears a break.
For all the strange twists “All I Want for Christmas Is You” has taken so far, they’ve all orbited around the tonic of G, with G major chords appearing at the beginning of each section (and at the midpoints of most sections). Songwriters frequently use bridges to establish contrast, and that’s exactly what Carey does with hers (beginning at 2:25). The bridge begins with a B7 chord on “All the lights are shining,” a V7/vi chord that heads, as expected, to vi on “brightly everywhere.” The rest of the bridge is closely related to the second half of the chorus, using a iv chord in first inversion (Cm/Eb) and a V7/ii chord (E7) before circling back to G for the beginning of a final verse.
Many aspects of “All I Want for Christmas Is You” sound like they came from the ’60s, including the bouncy piano figure after the intro and the heavily arpeggiated vocal melody. It’s no accident that the alternate version of the video features Carey dressed in gogo boots while singing the song from what might as well be the set of the Ed Sullivan Show. The song’s many harmonic twists also contribute to the feeling that the song comes from an earlier time, one where devices like secondary dominants and borrowed chords were used far more frequently than they are now.
Next chapter: Chicago, “You’re The Inspiration”