"Day after Tomorrow" was written by Tom Waits and his wife/collaborator Kathleen Brennan. It's one of the relatively few (for an artist with so much material) unambiguously political songs Waits has recorded.
The lyrics are written as a soldier's letter to his family. Speaking through the persona of the solder, Waits talks about missing the simple things back home and about how he'll be flying back there the day after tomorrow.
Waits mentions Rockford, Illinois, because he'd read a news article about a soldier who'd died in that town. The song wasn't specifically about that soldier, though. It was intended to be vague enough to be about any soldier in any war, though Waits was thinking predominantly about President George Bush's Iraq War, which was in full swing in 2004.
In discussing the distinction between an "anti-Bush" and an "anti-war" song, Waits told Vit Wagner of the Toronto Star in 2005, "In the end... it all comes to the same thing. Bush calls himself a wartime president, so if you're anti-war you're anti-Bush and if you're anti-Bush you're anti-war."
The song's not even limited to the wars of the Unites States. It's Waits' perception of all soldiers, which he has said are treated "like gravel" by the politicians who send them into combat.
There's a strange line in the song that doesn't seem to make any sense. In the final verse, Waits sings, "I'll be 21 today." The way to express that idea should be "I am 21 today," as "will be" is for things that will happen in the future. Whether or not this was a slip-up or if Waits had some other hidden meaning in mind is unknown.
At just under seven minutes long, this is the longest track on Real Gone.
Joan Baez covered this song on her 2008 album also titled Day After Tomorrow.