“There’s nothing I like more than finding our back catalogue in the prog section alongside Yes and Genesis… we wanted to show off every aspect of what we could do as artists”: Call them what you like, but Chicago know they’re a prog band

In a 2014 interview, Chicago co-founder and keyboardist Robert Lamm firmly rejected the notion that the band should be defined by their string of soft rock hits, insisting instead that Chicago has always been a progressive rock band at heart. He argued that tracks like If You Leave Me Now and Hard Habit To Break are merely part of a broader repertoire, comparing the mischaracterisation to reducing Yes to Owner Of A Lonely Heart or Genesis to Land Of Confusion, and said the band has always felt free to experiment musically without commercial pressure.

Lamm, who co-founded the group in 1967 as The Big Thing, traced this identity back to the band's origins as a university covers act in Illinois, where members reworked and extended Top 40 songs rather than simply mimicking them, eventually inspiring them to write original material. In 1968 they renamed themselves Chicago Transit Authority, relocated to Los Angeles and signed to Columbia through manager and producer James William Guercio. Mostly Autumn guitarist Bryan Josh also praised the band's ability to be convincing across both proggier material and mainstream hits, recalling first hearing them via If You Leave Me Now around 1976.