Jimmy Kimmel and Jay Leno explain Johnny Carson’s enduring influence

Johnny Carson was so popular during his heyday that a late-night quip about a toilet paper shortage caused a run on the product at grocery stores across the country in 1973, nearly a half-century before widespread pandemic hoarding of that important bathroom product. Such was Carson’s sway on our culture as host of “The Tonight Show” from 1962 to 1992.

“No one else has had that kind of influence,” says Jay Leno, who found himself at the center of a succession drama when he became Carson’s “Tonight Show” successor rather than David Letterman.

Jimmy Kimmel, another showbiz offspring of Carson, considers him the Abe Lincoln of late-night TV, his stature qualifying for Mount Rushmore status in the comedy world.

“There are a lot of presidents we don’t think much about because we’re always thinking about Lincoln,” says Kimmel, who has now spent two decades as a late-night host himself. Props should go to Steve Allen, who “invented the whole thing,” while Letterman gave the format an absurdist twist, “but Johnny was the most important,” Kimmel says. “Johnny was just such a part of the fabric of our lives.”

Carson at his peak averaged 9 million viewers nightly; Stephen Colbert now leads a crowded field with about 3 million. Even people too young to have watched Carson acknowledge his legacy. “He really was the monarch and owned the airwaves,” says Eric Andre, 41, who studied the master before launching his self-named Adult Swim show in 2012.

Now, some 32 years since Carson’s last show, heeeere’s “Carson the Magnificent,” a biography that tackles the comedian’s life and legacy. The project was so many years in the making that primary author Bill Zehme died before he could complete it.

“This was Bill’s white whale and I don’t believe he was ever going to finish it,” says Kimmel, who let the journalist live at his house for months at one point so he could focus on the book instead of celebrity interviews to pay the rent.

Zehme, who wrote for Rolling Stone and other major magazines, had authored books on Frank Sinatra and Andy Kaufman in addition to ghostwriting memoirs for Regis Philbin and Leno. A lifelong Carson fan, he conducted the final major interview with the “Tonight Show” host and originally planned to publish this book in 2007.

But he kept digging and digging in the hopes, Kimmel says, of trying to get under the skin of the oft-inscrutable Carson. Then Zehme got colorectal cancer and spent most of his last years battling the disease while trying to finish the book.

“He survived for almost a decade, but his health was never good enough to really dive back in,” says Mike Thomas, who finished the book after Zehme’s death. Thomas had worked for Zehme as a research assistant on the Sinatra, Leno, Philbin and Kaufman books before leaving for a career at the Chicago Sun-Times.

Zehme had about three-quarters of the book written and polished; Thomas used Zehme’s research and reporting to finish it.

“His daughter gave me the key to ‘Carson Land,’ a storage locker that was just jammed with binders, photos, records, even a big pink canceled check from Johnny to [band leader] Doc Severinsen,” Thomas says. “It was a matter of sifting through and figuring out what I needed to complete Johnny’s story.”

That story is neither hagiography nor hit job. “Johnny was a complicated guy, but his genius was undeniable,” Thomas says. “Bill got to the core of Johnny as much as anybody was going to, but he was in many ways an inscrutable guy.”

Zehme captures the magnificence of Carson the performer, the quintessential showman, who knew exactly what his audiences wanted, where the boundaries were and how to push them ever so lightly.

“Johnny always had these slightly risque jokes but had a great sense of what mainstream America would tolerate,” Leno says. “He knew just how far to push things.”

“He seemed so graceful and effortless the way he did the show,” Kimmel adds, “but there was so much about Johnny that I don’t think anybody living knows.”

In Zehme’s depiction, Carson’s public persona was a deception, a sleight of hand befitting a man who started as a magician and never lost his love for it. In private, he was not only cold and aloof but a lackluster father and a hard-drinking womanizer who, when under the influence, sometimes got physical with his wives.

“Occasionally he would wake the next day to discover that some such havoc had bruised the flesh of his sons’ mother,” one passage of the book reads.

“He was always nice to me,” Leno says, “but I know Johnny was not a good drinker and when he got drunk he got a little mean.”

Kimmel says the biography is “not a particularly flattering portrayal of Johnny, but it’s a fair one. And I think that’s probably good because we tend to turn people into caricatures. We think that person that you see on TV is that person. We all felt like we knew Johnny Carson, but we obviously didn’t.”

At one point in Zehme’s interview with Carson, the legend muses that if they asked younger people about “The Ed Sullivan Show” — once “the biggest show in America” — 31 years after it ended, “they look at you like it never existed. And why should they remember it?”

A similar interval after Carson’s last show, his ghost still lingers, and not just because of YouTube, where the icon’s estate has curated his clips.

“There’s enough clips of Johnny at his best that people can find whatever they want,” Leno says, although he notes that the jokes and flagrant sexism in many sketches feel dated.

Carson’s influence on everyone who followed remains enormous. On any given Monday, you might hear Jon Stewart briefly slip into an impression of him; other fans including Letterman and Conan O’Brien are still active on TV and podcasts, while the current crop of hosts — Kimmel, Colbert, Jimmy Fallon and Seth Meyers — are all old enough to have watched Carson growing up.

“They’re all living in the shadow of Carson,” Andre says, though he thinks this book will mostly reach boomers and Gen Xers. For his part, Thomas hopes the book can introduce a new generation to Carson’s work.

When he got his show, Kimmel went to the Paley Center in Beverly Hills, then called the Museum of Broadcasting, to watch Allen, Jack Paar and Carson.

“The number one thing I learned was that I would never be anywhere near as good as Johnny,” Kimmel says.

In his prime, Carson was the biggest star on the set, Kimmel points out. “Maybe Frank Sinatra would shop up and he and Johnny were equals, but that’s it. I can assure you that if Taylor Swift is on my show, it does not feel like we’re equals.”