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, starring Clint Eastwood. Herman Miller was responsible for the story of Coogan's Bluff and co-wrote the screenplay with Dean Riesner and Howard A. 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 appeared 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' most famous images.
NBC picked up the show for six 60-minute episodes in the fall of 1970, placing it in the rotation of its wheel series Four in One along with San Francisco International Airport, The Psychiatrist and Rod Serling's Night Gallery. The following fall, the network commissioned a new wheel series and lengthened McCloud from sixty to ninety minutes. NBC ordered two new series, McMillan & Wife and Columbo, to fill the wheel and all three became part of the new NBC Mystery Movie series, which aired on Wednesday nights. The series became a hit, finishing at number 14 for Nielsen ratings for the 1971–1972 season. NBC then decided to try another competitive move and relocated McCloud, along with McMillan and Columbo, to Sunday nights for the following fall. The Mystery Movie series was an even bigger draw on Sundays, finishing 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.
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".
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 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". Under his jacket or coat, he usually wore a khaki uniform shirt with a brown star-shaped uniform patch with gold trim on left sleeve. There was a yellow circle in the center with the number 33. He wore two collar pins one was "NM" and the other was "33". McCloud carried a blued .45 Colt SAA with a 4¾" barrel.
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!")
Another recurring theme in the show was the conflict between McCloud and his superior, NYPD Chief of Detectives Peter B. Clifford, played in every episode but the pilot by J. D. Cannon. In the first episodes, their relationship was portrayed as somewhat amiable, with Clifford showing a wary respect for the unconventional Westerner assigned to his command. The relationship quickly soured based mostly on McCloud's seeming disregard of authority combined with a charm that let him escape many of the consequences of his "cowboy-like" determination. Clifford's attitude to McCloud became one of cynical antagonism, bordering at times on extreme rage, but usually tempered with a grudging respect for McCloud's ability to solve the most difficult of cases. McCloud frequently interrupts a dressing-down from Clifford by saying "I 'ppreciate yer confidence, Chief!"
In many episodes, McCloud was partnered with Sgt. Joe Broadhurst, played by Terry Carter. Broadhurst, a New Yorker, was portrayed with a certain existential pessimism to counter McCloud's high spirits. Like Chief Clifford, Broadhurst felt himself wise to McCloud's peculiarities, but was without the anger, and usually wound up resigned to being drawn into McCloud's schemes to solve particular cases, sometimes against direct orders. He would then sometimes play the role of voluntary lightning rod for Clifford's anger, and absorb as much of the blame for McCloud's initiative as McCloud himself. (Broadhurst served as acting Chief of Detectives three times during Clifford's absence, in "This Must Be the Alamo", "Return to the Alamo" and "'Twas the Fight Before Christmas...".)
Other recurring characters on the show included the gravel-voiced Sgt. Grover, played by Ken Lynch, who seemed to be forever at his desk in the squad room. The ever-smiling but somewhat batty Sgt. Phyllis Norton was played by Teri Garr.
McCloud was portrayed as something of a ladies' man, and the characters played by the frequent female guest stars would often fall for his protective charm. Chris Coughlin, played by frequent guest star Diana Muldaur, was McCloud's off-and-on lover throughout the course of the series. Chris was a journalist whose duties as newspaper writer ("never a reporter") sometimes came into conflict with McCloud's police work.
The show, which was in some sense is a big city western, was set in New York City during what was arguably NYC's lowest point in the late 20th century, a period following the troubled 1960s and leading up to the fiscal crisis of 1975 (which figured, for example, in the episode "The Day New York Turned Blue"). The title card of the early seasons of the show prominently showed the Twin Towers of the World Trade Center still under construction, which at the time was a highly controversial urban regeneration project in the city.
At the time, the city seemed to be on an inexorable downward slide into chaos, a theme that was explored in a more brutal fashion in William Friedkin's film The French Connection which was released the year after the pilot of McCloud. In some episodes (such as "Walk in the Dark") the city was portrayed as particularly crime-ridden with the danger of muggings and bodily harm at every turn. Such lurking evil was often more in the dialogue than the pictures, however, and the show retained a somewhat whimsical and sunny flavor despite the subject matter.
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 and Teotihuacán 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").
Universal Studios Home Entertainment released Seasons 1 & 2 of McCloud on DVD in Region 1 and Region 2 in 2005/2006. Season 1 as released by Universal were not the original episodes but conflated “TV Movie” re-creations by Universal producer Harry Tatelman and editor Jean-Jacques Berthelot to extract additional revenues from a series considered too short of episodes to produce useful syndicated material. By editing together pieces from multiple episodes in season 1 it made it appear that McCloud solves two mysteries in each “movie”. Subplots and some characters were edited out. This process was made easier by the fact that McCloud’s uniform remained the same in each episode. The results were disjointed enough that at least one original writer, Douglas Heyes, required his name being changed in the credits to a pseudonym. These hybrid episodes were at one time considered all that was left of the original six programs of season 1 (Universal could not locate them when it issued the U.S. DVD set). The originals were located after a diligent search by the Australian independent label Madman Entertainment, found in good condition stored in a vault at a station in London. This is explained in greater detail at the classictvhistory web site 
It is unknown if the remaining seasons will be released in the U.S. at some point.
In Denmark (region 2) where McCloud was a hit when it was new, all 7 seasons have been released on DVD.
In Region 4, Madman Entertainment has released all seven seasons on DVD in Australia. Seasons 6 & 7 were released on June 19, 2013. The Season 7 release includes the reunion television film The Return of Sam McCloud.
The show is rated PG for Parental Guidance in Australia and PG in New Zealand for violence and drug references.
McCloud became the basis for a recurring joke on the movie-mocking TV series Mystery Science Theater 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 1970s 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. McCoy mentions the show was retooled after his character was written out to become Room 222.
McCloud has aired in reruns on local stations in the past, and continues to do so on some to this day.
Me-TV brought McCloud to its schedule as part of the late night "MeTV Mystery Movie" programming block which premiered on January 1, 2015. The network is employing a wheel arrangement similar to the original NBC Wednesday and Sunday Mystery Movie and rotates several other long-running programs from those including, McMillan & Wife, Columbo, Banacek, Quincy and the Perry Mason telefilms produced by NBC in the 1980s and early 1990s. Each week features five episodes from the featured series airing that week.