Maybe it was among the consequences of being a lifelong smoker that caused Gordon Lightfoot to briefly put down his guitar, make a self-deprecating remark and spray mist into his 78-year-old throat early in his Wednesday show at the Merrill Auditorium.

Whatever the reason and remedy, the voice became clearer as the show, his third in as many evenings, progressed.

OK, it wasn’t the rich baritone of years — heck, decades — past, but the Canadian legend showed that, while “Carefree Highway” can have its bumps, he’s yet to hit a dead end. He alternated between six- and 12-string guitars as he sang through more than 20 toe-tappers, chestnuts, ballads and a few soft rockers that resonated with the mostly older audience. Backed by a veteran four-piece band, Lightfoot kicked off the show with “Now and Then,” a wistful song best known to the so-called Lightheads, and followed it up with “Waiting for You” and “The Watchman’s Gone,” neither of which were radio staples this side of the 44th parallel, although not for lack of craftsmanship.

As he has done for years, Lightfoot abridged some of his most beloved songs to economize time and combined “Ribbon of Darkness” into a medley with “Sundown” that closed the first set.

His voice as good as a smoking senior citizen’s could be in the second set, as he performed some of his biggest hits, including “The Wreck of the Edmund Fitzgerald,” “Early Morning Rain” and, of course, “If You Could Read My Mind.” The newest member of the band, Carter Lancaster, who replaced the late Terry Clements on lead guitar in 2011, was especially strong, bending strings and layering the songs with that extra dose of emotion that made one feel the pain of infidelity, the doom of a sinking ship and the sense of abandonment one gets from watching a plane carry a loved one away.

Bassist Rick Haynes and drummer Barry Keane flawlessly anchored the rhythm section while keyboardist Mike Heffernan played tastefully and never drowned out what could be thin vocals. Those three men have been in the band for decades and obviously relish the work as much as does their venerable boss.

Ever available to a media he once shunned, Lightfoot has said he’ll keep touring as long as he has hair, and that he has down to his shoulders. He keeps a rugged schedule of 75 or 80 shows each year.

But there’s no denying that Lightfoot is aging. His face is gaunt, his limbs ropey like the late Pete Seeger’s and his once curly locks stringy. Having endured some serious health problems in his golden years, he seems to have simplified his guitar playing out of necessity and, while he still fills large venues in Canada, his U.S. concerts are no longer certain sellouts.

Whereas yesteryear’s shows were highlighted by heavy rhythmic songs — think “Canadian Railroad Trilogy,” “Old Dan’s Records” and his cover of Leroy Van Dyke’s “The Auctioneer,” none of which were heard Wednesday — fingerpicking seems to be his preferred modus operandi today. And while he rotates songs from his vast catalogue, he hasn’t released new ones in years.

Still, great tunes don’t have an expiration date, and Lightfoot’s best stand any test of time. To paraphrase one of his song titles, in his fashion he’s aging gracefully.

That may be best stated in “A Painter Passing Through,” a somewhat autobiographical, somewhat metaphorical look at his career and self-absorbed life before the onset of humility.

“Here comes Mr. Cool along the walk of fame,” goes a line from “Painter,” followed by verses about the aging process, the need for rest and how he’s just passing through in history.

A more literal and complete look at the icon from Orillia, Ontario, may emerge Sept. 26, when Toronto music writer Nicholas Jennings releases the first Lightfoot biography since a long out-of-print, late-1980s Maynard Collins effort with the predictable title “Lightfoot: If You Could Read His Mind.”

During a brief meet-and-greet after Wednesday’s show, Lightfoot smiled, said he consented to 26 interviews with Jennings, answered the same questions time after time, and hoped he would come across as an OK guy.

Gracious and in good humor, he sure seemed like one at the Merrill. “I couldn’t do this without you,” he responded when a rapturous woman expressed her admiration.

Among the early songs was a charming old ballad of a troubadour, complete with the kind of imagery that was so quintessential Lightfoot circa 1960s.

“The minstrel of the dawn is gone, I hope he’ll call before too long,” goes part of the final verse.

Such lyrics would have made for a fine encore, but the 1970s hit “Rainy Day People” got the nod for that.

Which was appropriate, too. After all, with his heavy touring schedule, Lightfoot always seems to know when it’s time to call. And his fans are not of the fair weather variety.

Neil Cote can be reached at:

ncote@mainetoday.com