Chicago’s music is timeless.

Heavily jazz-influenced, with tinges of classical in the slower numbers, the songs, some now more than 50 years old, likely still will be popular and as evocative 50 years from now.

That was the message from Chicago’s concert Friday headlining Bloomsburg Fair’s grandstand.

In a far-too-short (more about that later) 88-minute, 18-song show, there were few  weak moments; ­the least-potent perhaps being the opening song “Introduction” from the band’s 1969 debut disc — though that was played for effect. And even in it, the band’s instrumentation was sharp as you remember.

That was key to the night’s success: Even though there are only three originals among the band’s 10 members, all the players strongly delivered Chicago’s signature sound, which is really the whole point.

Noticeable was new (since 2018) tenor singer Neil Donell, who delivered vocals virtually equal to original singer Peter Cetera on hits such as the night’s second song, the band’s first single “Questions 67 and 68.” On the 1984 songs “You the Inspiration,” he held a long note and was rightfully cheered by the near-sellout crowd, and on “Hard Habit to Break” he pushed his voice and nailed the notes. On one of the night’s best, “Old Days,” he hit a nice falsetto.

But nearly all the players  had strong moments.

On the second song, 1972’s “Dialogue (Parts I & II),” original trombonist James Pankow had such energy that he swung his horn as he played, then mockingly wiped his brow. On the excellent 1971 hit “Beginnings,” Pankow and original trumpeter Lee Loughnane faced off against each other as original keyboardist Robert Lamm sang strongly. Loughnane also shined on a very good “Hard to Say I’m Sorry/Get Away.”

And a 10-minute version of the band’s 1971 hit cover of Spencer David Group’s “I’m a Man” started with bassist Brett Simons’s solo and included a five-minute percussion duel between percussionist Ray Yslas and drummer Walfredo Reyes Jr.

The crowd was so invested, it hardily cheered them on. Simply the opening notes drew reaction on the group’s  first Top 10 hit, 1969’s “Make Me Smile,” and again when it segued into 1971’s “Colour My World.” Also on “You’re the Inspiration” and one of the show’s best, 1973’s “Just You ’n’ Me.”

The band seemed infused with renewed energy after being sidelined by coronavirus.

“Yeah, Bloomsburg!” Lamm told the crowd early on. “We are so happy to be playing for some real people sitting in front of us. Let’s just have some fun.” Later, Pankow added, “We’re so damned glad to be back. We’re even more glad that you’re back.”

Chicago’s sound remained strong and fresh through the show, its riffs still connecting. Only “Now More Than Ever” sounded as if it had evolved, but still  was strong. Late in the show, the 1972 hit “Saturday in the Park” lagged a bit, but still was very good.

The only problem with a Chicago show is that the band’s catalog is so deep, favorites get squeezed out. On Friday, the band skipped 15 (!) Top 25 hits, including its first No. 1 “If You Leave Me Now,” “Baby What a Big Surprise” and “Love Me Tomorrow.”

Part of that might have been the later start as the fair seated the large crowd of 4,484 — 1,100 more than the fair's second-largest grandstand crowd — Jon Pardi on opening night). It wasn’t until after the fifth song, 23 minutes into the show that everyone was seated.

The main set closed with perhaps the night’s best, 1973’s “Feelin’ Stronger Every Day,” though it, too, was too short.

The encore opened with “Free,” not a bad song, but hardly the best. But it closed with “25 or 6 to 4,” which again sent a thrill through the crowd with its iconic opening riff, and was played very muscular — such a strong song, and a dream to finish with.

But the song that best told the story of the night came halfway though the show, the hit “Does Anybody Really Know What Time It Is?” It’s now more than 50 years old, but sounded fresh, and probably always will.

Because when it comes to Chicago’s music, there really is no time.