It takes a special kind of lawman to carry on for 20 years in the Wild West of TV.

Matt Dillon, the mythical marshal of Dodge City, stood tall — all 6 feet, 6 inches of him — on "Gunsmoke" from 1955 to 1975. He outlasted dozens of other Western heroes while making history on TV’s longest-running dramatic series, a record that held until NBC’s "Law & Order" tied the CBS Western’s record in 2010.

Through all those gunslinging years, James Arness, who died Friday, kept Marshal Dillon righteous, peace-seeking and, most of all, believable.

Fickle viewers can kill a TV hero as surely as a bullet from an outlaw’s six-gun. But Arness knew how to maintain order not only in circa-1870s Dodge City, but also among the TV audience, whose itchy fingers on their channel changers he knew how to calm.

In an era when TV actors typically chewed the scenery, Arness had a credible, commanding presence by hardly uttering a word. A typical scene found a dozen cowboys riding up to the town jail intent on busting out a prisoner pal.

Dillon faces them all down.

"The first move anybody makes," he says, with a slight shake of his head, "I cut you in two."

Arness’ defiant but rueful delivery is so understated, he makes Clint Eastwood seem like a loudmouth.

No wonder "Gunsmoke" wore so well. And became the last word on a programming craze that some seasons found as many as 30 Westerns on the air. When "Gunsmoke" went off in 1975, it was the only Western left.

By the end of his career, Arness, who was 88 when he died at his home in the Brentwood section of Los Angeles, seemed almost indistinguishable from Matt Dillon in the audience’s mind.

Befitting Marshal Dillon’s dignity and composure, Arness wrote, and left behind, a simple, straight-from-the-heart farewell which, at his request, was posted posthumously Friday on his official website.

"I had a wonderful life and was blessed with … (so) many loving people and great friends," he said, then went on to thank his multitude of fans.

In life, Arness was a quiet, intensely private man who preferred the outdoor life to Hollywood’s party scene, rarely gave interviews, and refused to discuss his personal tragedies (his daughter and his former wife, Virginia, both died of drug overdoses).

"He’s big, impressive and virile," co-star Amanda Blake (Miss Kitty) once said of Arness, adding, "I’ve worked with him for 16 years, but I don’t really know him."

The actor was 32 when friend John Wayne declined the lead role in "Gunsmoke" and recommended Arness instead. Afraid of being typecast, Arness initially rejected it.

"Go ahead and take it, Jim," Wayne urged him. "You’re too big for pictures. Guys like Gregory Peck and I don’t want a big lug like you towering over us. Make your mark in television."

Then Wayne filmed an introduction for the first episode of "Gunsmoke" to give the largely unknown Arness the proper send-off.

"I predict he’ll be a big star," Wayne told viewers. "So you might as well get used to him, like you’ve had to get used to me."

Arness’ 20-year, prime-time run as the marshal was tied only in recent times, by Kelsey Grammer’s 20 years as Frasier Crane from 1984 to 2004 on "Cheers" and then on "Frasier."

The years showed on the weathered-looking Arness, but he — and his TV character — wore them well.

"The camera really loved his face, and with good reason," novelist Wallace Markfield wrote in a 1975 "Gunsmoke" appreciation in The New York Times. "It was a face that would age well and that, while aging, would carry intimations of waste, loss and futility."

Born James Aurness in Minneapolis (he dropped the "u” for show business reasons), he and younger brother Peter enjoyed a "real Huckleberry Finn existence," Arness once recalled.

Peter, who changed his last name to Graves, went on to star in the TV series "Mission Impossible." (He died in 2010.)

A self-described drifter, Arness left home at age 18, hopping freight trains and Caribbean-bound freighters. He entered Beloit College in Wisconsin, but was drafted into the Army in his 1942-43 freshman year. Wounded in the leg during the 1944 invasion at Anzio, Italy, Arness was hospitalized for a year and left with a slight limp. He returned to Minneapolis to work as a radio announcer and in small theater roles.

He moved to Hollywood in 1946 at a friend’s suggestion. After a slow start in which he took jobs as a carpenter and salesman, a role in MGM’s "Battleground" (1949) was a career turning point. Parts in more than 20 films followed, including "The Thing," ”Hellgate" and "Hondo" with Wayne. Then came "Gunsmoke," which proved a durable hit and a multimillion-dollar boon for Arness, who owned part of the series.

His longtime co-stars were Blake as saloon keeper Miss Kitty, Milburn Stone as Doc Adams, Dennis Weaver as the deputy, Chester Goode, and his replacement, Ken Curtis, as Deputy Festus Haggen.

The cancellation of "Gunsmoke" didn’t keep Arness away from TV for long: He returned a few months later, in January 1976, in the TV movie "The Macahans," which led to the 1978-79 ABC series "How the West Was Won."

Arness took on a contemporary role as a police officer in the series "McClain’s Law," which aired on NBC from 1981-82.

Despite his desire for privacy, a rocky domestic life landed him in the news more than once.

Arness met future wife Virginia Chapman while both were studying at Southern California’s Pasadena Playhouse. They wed in 1948 and had two children, Jenny and Rolf. Chapman’s son from her first marriage, Craig, was adopted by Arness.

The marriage foundered and in 1963 Arness sought a divorce and custody of the three children, which he was granted. He tried to guard them from the spotlight.

"The kids don’t really have any part of my television life," he once remarked. "Fortunately, there aren’t many times when show business intrudes on our family existence."

The emotionally troubled Virginia Arness attempted suicide twice, in 1959 and in 1960. In 1975, Jenny Arness died of an apparently deliberate drug overdose. Two years later, an overdose that police deemed accidental killed her mother.

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AP Television Writer David Bauder and Entertainment Writer Jake Coyle in New York, and Television Writer Lynn Elber in Los Angeles contributed to this story.