"45" was the first song written for Handwritten. Lead singer, Brian Fallon said of the song, "This record was different, because when we started out, I didn't know what was gonna happen, you know, and after American Slang after The '59 Sound, I was like, 'What am I gonna do? Is there anymore Gaslight songs?' It's a scary thing when that feeling, it hits you. When we wrote the song '45', I was like, 'Thank God.' I just knew that it was gonna be alright."