Chicago's "If You Leave Me Now" hit number one on October 23, 1976. The song, a track from the band's "Chicago X" album, was the group's first tune to hit number one on the Billboard Hot 100.The jazz-rock group had seen significant success with their albums, including a string of five consecutive number-one LPs in the first half of the 1970s. They also had several tunes break the top ten on the singles chart (with "Saturday In The Park" notching their previous best performance, reaching number 3).Ironically, while "If You Leave Me Now" became the band's first number-one single, "Chicago X" broke the group's number-one album streak. The LP peaked at number 3; this would turn out to be the last time a Chicago album would chart that high.