I don’t know if this has been covered here yet, but it led to a lively discussion this weekend on Facebook. What key would you say this classic Lynyrd Skynyrd song is in and why? Looking forward to some great Straight Dope wisdom here.
D or G, depending on how you look at it.
And how do you look at it?
I think both D and G would be acceptable answers, but I’d probably go for D.
The song repeats a cycle of half a bar in D major, half a bar in C major and a whole bar of G major. So G major plays for twice as long as D major. Viewing the song as being in G major produces the major scale/Ionian mode.
However, it’s a rock song and the Mixolydian mode, which is like the major scale but with a flattened 7th, and which is produced by viewing the song as being in D, is the quintessential rock scale. If I was going to add a section, such as an instrumental section to the song, but played on a single chord, I think I’d choose D major, rather than G major, as that feels more like the root note to me.
Adam Neely thinks D, although he also thinks a quantum superposition of G and D.
Sounds like D to me but the video at the link shows Skynyrd ending the song live on the G chord so they seem to disagree.
It’s in G. One sharp (F#) in the key signature.
But that also describes the key of D using the Mixolydian mode.
The question centers around whether one considers the D chord or the G chord as the root chord.
Tagg analyses it as a common “three-chord Mixolydian loop in D”. He mentions, for instance, an anacrusis containing a repeated a–b–d pattern propelling movement towards the tonic D chord.
It’s in D mixolydian. The chords are ambiguous, but the melody pretty clearly resolves to D. In fact, unless I missed it, there is no G in the melody at all.
This.
It also comes down to which chord (and tonic) feels like home, doesn’t it? People often focus on the chord progression but neglect to also look at the what the melody is doing.
I was surprised by that as well. G does not fer like home to me in this song .
There are number of modes that have one sharp in the key signature but are not G major, including E minor and D mixolydian.
Bingo. In fact, in the key of D, it’s mostly a do-re-mi melody, beginning on the third of the scale. If it’s in G, then it’s starting on the major 7th scale degree, an unusual place to start.
The same book of Tagg’s says that “The main point here is that if musicians can opt to end on either what they perceive as the tonic or on the last chord of the loop in question, then the harmonic finality marker in live performance is not necessarily the loop’s tonic.” 
It’s an interesting song to me and it sounds like Ed King, co-writer and lead guitarist in this song, believed it was in G. He plays the solo like it’s in G, particularly with the Neil Young style high G note during the solo, but the melody of the singer certainly seems to suggest D. It has the same chord progression as “Werewolves of London” and “All Summer Long,” both of which feel like G. In fact WoL has pretty much only G in the melody, whereas SHA does not have a G even once in the melody.D mixolydian makes more sense to my ears.
More interesting than one might think:
I strongly hear D as the tonic.
Schrödinger’s key!
Interesting how often famous songs, or at least part of them, like a riff or melody, came to the songwriter in a dream. I can think of two other examples off the top of my head:
Sure seems that way!