James Arness, the Minnesota city boy who became television's strongest, most stoic symbol of the Old West, died Friday at age 88 of natural causes.

Arness was best known for the role of straight-shooting straight-arrow U.S. Marshal Matt Dillon, the lead character in "Gunsmoke," which ran on CBS from 1955 to 1975. It's tied with "Law & Order" as the longest-running dramatic series in network history.

Born James Aurness (he dropped the "u" when he took up acting), he grew up in south Minneapolis and attended John Burroughs Elementary and Washburn and West high schools. His younger brother, Peter Graves, who died last year, found fame on his own terms as the star of "Mission: Impossible."

Arness, who rode tall in the saddle at 6 feet 7, was hired to play Dillon on the recommendation of his mentor, John Wayne, who made a rare TV appearance to introduce the very first episode. Before being taken under Wayne's wing -- they made four films together in the 1950s -- he fought in World War II and appeared in more than 20 films.

When the show premiered in 1955, mother Ruth Aurness told the Star Tribune that she was distressed about the kind of character her son had signed up to play. "But I suppose I have to think about his career," she said.

"Gunsmoke" would go on to become the quintessential Western, with Arness as a small-screen Gregory Peck. It was television's most-watched show from 1957 to 1961. Thirty Westerns came and went on TV during its unprecedented run.

Arness, who rarely agreed to interviews, credited much of his success in playing tough characters to his Minnesota upbringing.

"It must be the Viking blood in me," the Norwegian-American actor said in 1955. "I'm always thinking about the times I sailed my sailboat in [Lake] Calhoun when I was going to West High."

His personal life wasn't as fortunate as his professional one. His ex-wife Virginia and daughter Jenny both died of drug overdoses. He is survived by his second wife, Janet, two sons and six grandchildren. A private memorial service will be held in California.

The Associated Press contributed to this report. njustin@startribune.com • 612-673-7431 • On Twitter: @nealjustin