With grace and sly charm, Garrison Keillor prepares to exit ‘Prairie Home Companion’

Whispery and wise and flecked with eccentric humor, Garrison Keillor’s baritone has long seeped across a nation that, despite its perpetual restiveness and cravings for trends, has found comfort in his brand of Midwestern pragmatism, schmaltz and slow-motion charm.

The voice, which has the timbre of a great-uncle sharing confidences in the pitch of night, is about to pack up its tales and retire after four decades. Keillor has announced that after next season he will no longer host “A Prairie Home Companion” radio show, which features music, drama and skits from Lake Wobegon, a fictional Minnesota town where “all the women are strong, all the men are good-looking and all the children are above average.”

That kind of humor, crisp as dry air and too down-home for some, has been Keillor’s signature, his version of America, its moods, whims, wants and yearnings. A writer and humorist often compared to Mark Twain, Keillor, with his lanky frame, red socks and bushy eyebrows, is at once folksy and erudite, a disheveled man at the middle of a secret. His show is broadcast to about 4 million listeners on nearly 700 public radio stations and other outlets.

When asked by email Tuesday why he chose to retire — it had been hinted at for years — Keillor responded with characteristic aplomb. “I had a bad moment on the show and completely screwed up the bridge of ‘Wouldn’t It Be Nice’ and thought, ‘Don’t let this go on too long,’ ” he said. “I’m almost 73, and people my age are getting weird problems, sciatica and stenosis and Sisyphean syndrome.”

Keillor will be replaced in 2016 by Chris Thile, a mandolin player with the bands Nickel Creek and Punch Brothers, who has guest-hosted the show in the past. The selection suggests that the program may return to more of a musical variety show. In a statement, Thile, 34, said, he and Keillor discussed the future of the show and agreed that “we should give it a go. There are, of course, plenty of details to iron out, but, but I’m very excited.”

Keillor said of Thile: “Fabulous musician, enthusiastic about live radio, and a good soul. He’s tanned and ready to go. I’m ready to sit down.”

“A Prairie Home Companion” is distributed by American Public Media and broadcast mainly from the Fitzgerald Theater in St. Paul, Minn. It features traditional and folk musicians and sketches, including yarns and satires about ministers, waitresses, cowboys, Norwegian farmers and the little town of Lake Wobegon “that time forgot and the decades cannot improve.” One of his most popular characters is Guy Noir, a fictional detective who tracks down missing poodles and encounters sultry women.

“She wore a knit sweater and jeans so tight it looked as if she had been poured into them and forgot to say ‘When,’ ” Keillor voices as Guy Noir in one scene. “When she moved, she seemed to undulate under her clothes in ways that took a man’s mind off the state of the economy.”

One of Keillor’s skills — his wit and voice can, depending on the listener, be either soothing or cloying — is making the local seem universal.

“He found the middle of America, and he represented it as a culture that truly matters to everyone, from coast to coast,” said Gary Scott, program director for KCRW-FM in Santa Monica. “His work might have seemed unassuming at first, but any careful study would show just how much craft goes into the sound. That’s what resonated beyond geography — the craft of great radio.”

Scott added that that Keillor’s popularity is his ability to force us to “see ourselves, our prejudices, silliness and character flaws. ... No one in [public radio] has really been able to reach that level.”

Director Robert Altman captured the zaniness of “A Prairie Home Companion” is his 2006 film of the same name. The movie starred Tommy Lee Jones, Meryl Streep, Kevin Kline, Lily Tomlin and Keillor, who wrote the screenplay.

Writing in the New York Times, critic A.O. Scott said of the movie: “Notwithstanding the occasional crackle of satire or sparkle of instrumental virtuosity, it mostly offers reliable doses of amusement embedded in easygoing nostalgia. It looks back on — or, rather, reinvents — a time when popular culture was spooned out in grange halls and Main Street movie palaces, and when broadcasting was supposedly a local affair sponsored by mom-and-pop purveyors of biscuits and Norwegian pickled herring.”

In his email, laced with sly charm and a coming to terms with age, Keillor put the reason for his retirement in a poem:

I decided today to resign.

I am not, after all, 69.

I want to retrench a

Few steps ere dementia,

And I want the idea to be mine.