The first choice for the role of McCloud was Fess Parker who turned it down. Universal hired the highly experienced Dennis Weaver. The pilot, "Portrait of a Dead Girl", aired on February 17, 1970, and established the premise by having McCloud escort a prisoner from New Mexico to New York City only to become embroiled in solving a complicated murder case.
This premise of "a cowboy in the big city" was more or less adapted from the 1968 Don Siegel film, Coogan's Bluff that starred Clint Eastwood. Herman Miller was responsible for the story of Coogan's Bluff and co-wrote the screenplay with (Dean Riesner and Howard Rodman (indeed, Miller is credited as the creator of McCloud). Coogan's Bluff reflects Richard Thorpe's 1942 film Tarzan's New York Adventure and the latter-day career of Bat Masterson. (Siegel himself appears in the "Return to the Alamo" episode as "2nd Desk Sergeant".) Like Coogan, McCloud galloped the length and breadth of Manhattan (he was joined by a mounted unit in "The 42nd Street Cavalry"), and the sight of McCloud on horseback riding down the middle of a busy street (taken from an early episode) became one of the series' iconic images.
NBC renewed the show for six 60-minute episodes in the fall of 1970, placing it in the rotation of its "wheel format" series Four in One, along with Night Gallery, San Francisco International Airport, and The Psychiatrist.
In the fall of 1971, NBC placed McCloud, along with two other new series, McMillan & Wife and Columbo, in the rotation of a new drama NBC Mystery Movie which aired on Wednesday night from 8:30–10:00. The running time of each episode was increased to 90 minutes. The umbrella series was a success, finishing at number 14 for Nielsen ratings for the 1971–72 series. The following season, NBC moved McCloud and the other two shows of Mystery Movie to the competitive 8:30–10:00 Sunday night position and added a fourth series, Hec Ramsey to the rotation as the NBC Sunday Mystery Movie. The rotating series was an enormous success and finished at number 5 in the ratings for the season.
Starting in the fifth season in the fall of 1974, the episodes were two hours long, but were dropped again to 90 minutes for the seventh and final season starting in the fall of 1976. The 46th and last episode, "McCloud Meets Dracula", was aired on April 17, 1977.
Dennis Weaver received Emmy nominations in 1974 and 1975 for Outstanding Lead Actor in a Limited Series.
The executive producer was Glen A Larson, who also wrote for the series (as did Peter Allan Fields, Lou Shaw, Jimmy Sangster, and others). Larson won an Edgar Award for "The New Mexican Connection".
Since leaving the air in 1977, the show has played regularly and often in syndication. In 1989, Weaver reprised the role in a made-for-television movie, The Return of Sam McCloud, in which his character was now a United States Senator. It first aired on November 12, 1989. Diana Muldaur, fresh from Season Two of, Star Trek: The Next Generation, returned to reprise her role as McCloud's love interest, Chris Coughlin.
The most enduring theme of the show was the conflict between the good-natured, clear-eyed buoyancy of McCloud and the metropolitan cynicism of the residents of New York City, including his fellow officers. McCloud's attire, typically consisting of a sheepskin coat or Western jacket, bolo tie and cowboy hat, allowed for implied comic relief in many encounters with New Yorkers. That New Yorkers might mistake him for a naïf because of his appearance occasionally worked to his advantage. He would often allay suspicion of his motives by insisting he was in New York "to observe and learn".
The signature of McCloud's character was his Western unflappability and seeming inability to recognize an insult, especially from Clifford, whose jibes ("send in the sagebrush Sherlock Holmes") he never would take personally. Weaver's grin and drawling twang represented McCloud as the embodiment of the American law officer who always sees the good in people but knows the real stakes and spares no pain to catch the bad guy. The character's signature catchphrase was "There ya go!", often received with bemusement or puzzlement by the listener. (One exception was a character played by John Denver; at the end of the show they traded catchphrases, Denver responding "There ya go!" to McCloud's "Far out!")
McCloud was filmed partially on location (the unit was in New York for "A Little Plot at Tranquil Valley" notably, and traveled to Hawaii for "A Cowboy in Paradise", to Mexico City for "Lady on the Run", and to Sydney for "Night of the Shark" — second-unit footage came from London, Paris, Monaco, Rome, and Moscow at various times), but utilized the Universal back lot for many scenes.
A recurring theme in many episodes was the incorporation of a plot device from Hollywood Cinema particularly at the climax of an episode. Examples included chases on horseback to lasso cattle rustlers ("The Colorado Cattle Caper"), a 1930s-style gangster shoot-out (the film-within-a-film shot on location in "The Gang That Stole Manhattan,"), a Jesse James - style train hold-up on the Long Island Rail Road ("Butch Cassidy Rides Again"), and a showdown with a vampire on the Third Street Bridge ("McCloud Meets Dracula").
McCloud became the basis for a recurring joke on the movie-mocking TV series Mystery Science Theatre 3000: whenever one character in the featured movie would call out to someone else, host characters Joel Robinson, Tom Servo and Crow T. Robot would chime in by calling out to other unrelated fictional characters such as Mr Drysdale and "Mr. Eddie's Father". Invariably, these exchanges ended with Servo calling "Chief?" and Crow responding with "McCloud!" The gag was most prominently featured in episode 303, "Pod People".
On an episode of The Simpsons, "The Lastest Gun in the West", Weaver guest-stars as an old-time cowboy star named Buck McCoy, who in the '70s had starred on a detective show called "McTrigger", about which McCoy admits, "Seems all I did was shoot hippies." A clip showed McTrigger driving through New York in a convertible shooting at random members of the hippie crowd that covered the sidewalks.