“Truckin'” stands as one of the Grateful Dead’s densest tunes lyrically speaking, and in a new piece for The Wall Street Journal, Bob Weir broke down the backstory to the song starting with its inspiration drawn from the band’s rigorous touring schedule of the late 60s and early 70s.

“[Our touring schedule] was relentless,” Weir said. “We’d play a gig, stay up late and then fly to our next gig first thing in the morning. Most of the time, our equipment was trucked overnight to the next destination.” He referred to that time, of traveling, playing and partying as an “endless cycle” that sparked inspiration in lyricist Robert Hunter.

After handing the lyrics to what would become “Truckin'” to Jerry Garcia, the guitarist “liked what he read, and we planned to work on the music as soon as we had some down time.”

Weir notes some of the references in the lyrics, like the song’s title coming from one of R. Crumb’s underground comic characters. “Mr. Natural had a bunch of sayings. One of them was ‘Keep on Truckin’,’ which was the spirit of our song.”

There are also more obvious references to the band’s infamous arrest in New Orleans, Dallas’s “soft machine” police and Houston being “too close to New Orleans.” Weir says the listener is free to “make up your own doo-dah man” in the lyrics as well. “I don’t know who ‘Sweet Jane’ was. I have a feeling it wasn’t Janis Joplin,” Weir also said. “It was some sorority girl who found her way into a little dead-end alley in the hippie culture. Each of us had our own individual Sweet Jane and probably still do.”

Weir continues with the song breakdown, like how the “reds” reference red Seconal pills the band would take to fight insomnia (“The bikers were using them as a recreational drug”) and how the tune took on its “bluesy shuffle” along with Weir, Phil Lesh and Garcia worked up the vocal harmonies while sitting by the pool in Florida.

Read Weir’s full account here.