Chicago’s history can be divided into two eras. Before the 1978 death of guitarist and founding member Terry Kath, Chicago was primarily known as a septet instantly identifiable by the sounds of its horn arrangements on hits such as “24 or 6 to 4,” “Does Anybody Really Know What Time It is?” and “Saturday in the Park.” The band practically defined adult contemporary music after scoring a No. 1 hit in 1982 with “Hard to Say I’m Sorry,” with Peter Cetera taking lead vocal on a subsequent string of David Foster-produced hits. Cetera went solo in 1985, but the band carried on with four original members through the 50th anniversary of its formation in 1967.

Founding saxophonist Walter Parazaider retired last year due to a heart condition, but three original members continue to carry on the legacy as Chicago appears at The Venetian Theatre for a multidate engagement. It’s not the first time keyboardist-singer Robert Lamm, trumpet player Lee Loughnane and trombonist James Pankow have unpacked their bags for an extended stay on the Strip, as Chicago scheduled two 10-concert runs at MGM Grand’s Hollywood Theatre in March and May 2006. Things are different this time, as Chicago’s latest Vegas sojourn comes after being inducted into the Rock and Roll Hall of Fame in 2016 and on the heels of the premiere of a career-spanning documentary on CNN in September.

Now More Than Ever: The History Of Chicago, directed by Chicago keyboardist Lou Pardini’s nephew Peter, traces the band’s career from its Windy City beginnings as The Big Thing through its evolution as the college campus favorite Chicago Transit Authority to its latter-day lineup changes as it remains a successful touring act in its 51st year. The documentary also focuses on the faces and personalities present behind the music, which were purposely downplayed for much of the band’s career.

Individual founding members get their due in the film, which was added to Netflix last month, as does the Kath era. Much of the music in the current set list comes from this time, with ’80s ballads including “Hard Habit to Break” and “You’re the Inspiration” handled by new tenor Neil Donell. Percussionist Walfredo Reyes Jr. recently took over on drums, pounding out beats that founding drummer Danny Seraphine originated on signature songs such as “I’m a Man” and “Feelin’ Stronger Every Day.” Many of the songs in recent sets have been deep covers from early albums, much to the pleasure of longtime listeners who bought vinyl copies of Chicago III, IV and V in the early ’70s.

Lamm, Loughnane, Pankow and Parazaider reckon with their collective past, wax nostalgically about encounters with Jimi Hendrix and Janis Joplin, mourn Kath’s death by accidental shooting, diss a few former members and generally set the record straight the way they see it. Chicago’s current set represents the founding members’ idea of what, in the end, the band is all about. It’s rock ’n’ roll with horns, and no other band did it better.

The Venetian, 8 p.m. Feb. 7, 9-10, 14, 16-17, 21 & 23-24, starting at $59 plus tax and fee. 702.414.9000