“Tom Petty wrote dozens of hit songs over the course of his four-decade career as frontman of the Heartbreakers, but not all of them impressed his bandmates. At least not right away,” (Ultimate Classic Rock). “Such was the case with ‘Mary Jane’s Last Dance,’ a song that Petty started one day and didn’t finish. ‘I wrote all but the chorus,’ he recalled for 2005’s Conversations With Tom Petty. ‘I just had the loop going around and around and really had most of the words and everything. And I played the tape for Rick [Rubin] and he liked it a lot and suggested I write a chorus. So I tried to finish it up while I was making [1994’s] Wildflowers, and there were maybe five years between the writing of the verses and the chorus.’
… For those who hastily assumed ‘Mary Jane’ was a reference to marijuana, Petty cleared that up later on. ‘I don’t think I was writing about pot,’ he said in 2005. ‘I think it was just a girl’s name. I can’t imagine that I’d write a song about pot. I don’t think there’s enough there to write about [laughs].’ Though it took years for ‘Mary Jane’s Last Dance’ to take its final form, it clearly paid off. By the time Petty died in 2017, the band had played the song live in concert over 500 times, and it’s remained an important touchstone of their catalog.”
Starting with an intro and verse in an uptuned A minor, the chorus (first heard from 1:09 – 1:31) shifts to A major — somewhat obscured by a prominent minor v chord (E minor).