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Chicago is an American rock band formed in 1967 in Chicago, Illinois as The Chicago Transit Authority before shortening the name in 1970. The self-described "rock and roll band with horns" began as a politically charged, sometimes experimental, rock band and later moved to a predominantly softer sound, generating several hit ballads. The group had a steady stream of hits throughout the 1970s and 1980s. Since at least 2008, Billboard has shown Chicago to be the "greatest of all time" American band in singles chart success, and since 2015, the "greatest of all time" American band in album chart success as well.

The year 1978 began with a split with Guercio. Chicago had recorded its last five studio albums Chicago VI, VII, VIII, X, and XI, and had made two television specials at Guercio's Caribou Ranch. In later years, band members would cite Guercio's purchase of Caribou Ranch, more particularly their realization that Guercio had enough money to purchase Caribou Ranch, as a contributing factor to their disillusionment with him as a producer. They felt he had taken advantage of them financially. Then on January 23 of that same year, Kath died of an accidental, self-inflicted gunshot wound from a gun he thought was unloaded. 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. According to writer Jim Jerome, the visit "snapped them back" and helped them make the decision to carry on.  After auditioning over 30 potential replacements for Kath, Chicago decided upon guitarist and singer-songwriter Donnie Dacus. While filming for the musical Hair, he joined the band in April 1978 just in time for the Hot Streets album. Its energetic lead-off single, "Alive Again", brought Chicago back to the Top 15; Pankow wrote it "originally as a love song but ultimately as recognition of Kath's guiding spirit shining down from above."  The 1978 album Hot Streets was produced by Phil Ramone. It was Chicago's first album with a title rather than a number; and was the band's first LP to have a picture of the band (shot by photographer Norman Seeff) featured prominently on the cover (with the ubiquitous logo downsized). These two moves were seen by many as indications that the band had changed following Kath's death. To a degree, the band returned to the old naming scheme on its subsequent releases, although most titles would now bear Arabic numerals rather than Roman numerals. Hot Streets, the band's 12th album, peaked at No. 12 on the Billboard charts; it was Chicago's first release since their debut to fail to make the Top 10. The release also marked a move somewhat away from the jazz-rock direction favored by Kath and towards more pop songs and ballads. Dacus stayed with the band through the 1979 album Chicago 13, and is also featured in a promotional video on the DVD included in the Rhino Records Chicago box set from 2003. Again produced by Ramone, it was the group's first studio album not to contain a Top 40 hit. Dacus departed from the band shortly after the album's release.
Chicago (band)