Growing out of several bands from the Chicago area in the late 1960s, the original line-up consisted of Peter Cetera on bass, Terry Kath on guitar, Robert Lamm on keyboards, Lee Loughnane on trumpet, James Pankow on trombone, Walter Parazaider on woodwinds, and Danny Seraphine on drums.

[27][28] The group now known as Chicago began on February 15, 1967, at a meeting involving saxophonist Walter Parazaider, guitarist Terry Kath, drummer Danny Seraphine, trombonist James Pankow, trumpet player Lee Loughnane, and keyboardist/singer Robert Lamm.

In June 1968, at manager James William Guercio's request, the Big Thing moved to Los Angeles, California,[32] where they signed with Columbia Records and changed their name to Chicago Transit Authority.

[12] While performing on a regular basis at the Whisky a Go Go nightclub in West Hollywood, the band got exposure to more famous musical artists of the time,[33] subsequently opening for Janis Joplin and Jimi Hendrix.

[14] Along with the four vinyl discs, the packaging contained some strident political messaging about how "We [youth] can change The System", including wall posters and voter registration information.

[46] Drummer Danny Seraphine attributes the fact that none of Chicago's first four albums were issued on single LPs to the productive creativity of this period and the length of the jazz-rock pieces.

[78][79][80] In July 1973, the group starred in a half-hour television special produced by Dick Clark, Chicago in the Rockies, which aired in prime time on ABC.

[86][87] Doc Severinsen, who was the bandleader for The Tonight Show Starring Johnny Carson at the time and a friend of the group, visited them after Kath's funeral and encouraged them to continue.

[88] Its energetic lead-off single, "Alive Again", brought Chicago back to the Top 15;[20] Pankow wrote it "originally as a love song but ultimately as recognition of Kath's guiding spirit shining down from above".

According to Jeff Giles, "Although Chicago quickly soldiered on [after Kath's death], releasing their Hot Streets album with new guitarist Donnie Dacus that October, it was impossible not to notice the loss of momentum.

[92] Chicago XIV (1980), produced by Tom Dowd, relegated the horn section to the background on a number of tracks, and the album's two singles failed to make the Top 40.

[54] Believing the band to no longer be commercially viable, Columbia Records dropped them from its roster in 1981 and released a second greatest hits volume (counted as Chicago XV in the album chronology) later that year to fulfill its contractual obligation.

For the 1982 album Chicago 16, the band worked with composers from outside the group for the first time, and Foster brought in studio musicians for some tracks (including the core members of Toto),[95] and used new technology (such as synthesizers) to "update" and streamline the sound, further pushing back the horn section, and in some cases not even using them at all.

The single, "Hard Habit to Break", brought two more Grammy Award nominations for the band, for Record of the Year and Best Pop Performance by a Duo or Group with Vocals.

[103][104] He soon topped the charts with "Glory of Love" (the theme song of the film The Karate Kid Part II), and with "The Next Time I Fall" (a duet with Amy Grant).

In 1992, Cetera released his fourth studio album, World Falling Down, which earned him three hits on the Adult Contemporary charts, including the single "Restless Heart".

[123][124][125] The album featured guest appearances by Paul Shaffer of Late Show with David Letterman fame, Aerosmith guitarist Joe Perry, and The Gipsy Kings.

[149] In late 2013, the band began releasing singles for a new album, starting with "Somethin' Comin', I Know" in August, "America" in September, "Crazy Happy" in December 2013, and "Naked in the Garden of Allah" in January 2014.

[155] In February 2016, it was announced that original drummer Danny Seraphine would join the current lineup of Chicago for the first time in over 25 years for the Hall of Fame Induction Ceremony.

[177][178] Chicago began their 2018 touring schedule on Saturday, January 13 by performing the grand opening concert at the new Xcite Center at Parx Casino in Bensalem, Pennsylvania.

[180] On Friday, January 19, 2018, bassist and vocalist Jeff Coffey announced on his Facebook page that he was also departing from the band due to its heavy touring schedule.

[208] During his discussion of the formation of the band, original drummer Danny Seraphine says he wanted to form a group of talented, skilled musicians, with a horn section, "that could play an inventive mix of rock and jazz.

"[212] On the occasion of the band's 50th anniversary, Bobby Olivier, writing for Billboard, described its style as "chameleonic ... shifting from esoteric jazz-rock, funk and soul to  ... adult contemporary ...".

"[91] In a 2021 interview published in Prog, Robert Lamm asserts that Chicago is and always has been a progressive rock band and that they were particularly influenced by Yes and King Crimson to write and record their lengthier tracks.

[215] When asked why the band didn't continue in its "jazzy improv" direction, Loughnane voiced his opinion that how the songwriters wrote was "materially affected" by changes in payment of royalties by the record companies and by the relatively short airplay time allowed for a song on the radio.

[219][220][221][222] The group gave a benefit performance for Musicians on Call, on Sunday April 23, 2023, held at the Hard Rock Cafe in Times Square in New York City.

For example, it appeared as an American flag on III, a piece of wood on V, a U.S. dollar bill on VI, a leather relief on VII, an embroidered patch on VIII, a chocolate bar on X, a map on XI, a building on 13, a fingerprint on XIV, a computer silicon chip on 16, a parcel on 17, a mosaic on 18, and an aquarelle on 19.

[261] The book titled Type and Image: The Language of Graphic Design described the logo as "a warm vernacular form, executed in thick script letters with Victorian swashes in the tradition of sports teams and orange crate labels".

[170] The legal hierarchy of the band was illuminated in a July 2022 published interview with Robert Lamm, in which he, Pankow and Loughnane are identified as the "partners" and the rest of the members as "contracted players".

[4] While Parazaider at times had been referred to as a non-touring member of the group,[264] he did not appear on either of the studio albums released since his retirement, 2019's Chicago Christmas,[194][265] and 2022's Born for This Moment.