The funniest ten minutes ever are in store for radio fans this evening with the first appearance over W-G-N., The Chicago Tribune station on the Drake hotel, of "Sam n' Henry," the two characters in the station's new radio comic strip.
--Chicago Tribune, January 12, 1926

The creators of Amos 'n' Andy, Charles Correll and Freeman Gosden, were regulars in the broadcast area of the Chicago Tribune's WGN (World's Greatest Newspaper) in the mid-1920s. After years of working the vaudeville circuit, they began performing songs and blackface comedy bits on a semi-regular basis. Early examples of their work include:

One day, however, they were approached by Ben McCanna, an executive at the Tribune and Henry Selinger, WGN's program director. The two were interested in developing a serial radio drama similar to the popular daily comic feature, the Gumps. The value of a newspaper producing such a series is explained by Michele Hilmes in her book, Radio Voices:

As interest in the medium rose to ever-greater heights, a radio outlet could be used to draw readers to the newspaper for schedules, promotions, scripts, comics, advertising tied to popular radio features, and promotion for the newspaper in general. In turn, radio programs on newspaper owned stations enjoyed an immediate and crucial advantage over those with different ownership: free, motivated, and frequent publicity. (p 83)
While Correll and Gosden were interested in developing a series, they didn't think basing it on the Gumps was the way to go. Instead, they suggested the story of two black men migrating to the North in search of work. McCanna and Selinger bought the idea and Sam n' Henry debuted a few months later.

The live broadcast--10 minutes a night, 6 nights a week, with the duo writing all of the scripts and supplying all of the character voices-- focused more on the development of characters than a series of one gag after the next. This serial format, new to the airwaves, was an immediate success. Some examples of the early shows include:

As its popularity grew, the newspaper found a number of ways to capitalize off the program. Melvin Ely notes in his social history, The Adventures of Amos n' Andy:
The Tribune found new ways to profit from the team's popularity. Every Sunday during much of 1927, the newspaper published the script of a current Sam n' Henry episode, written in a "dialect" and accompanied by caricatures of the principal characters in action. The paper used the feature as one of the main selling points for its new Metropolitan Section--a weekly collection of humor columns, adventure narratives, and other attractions--and it syndicated the Sam n' Henry column to other newspapers. The Tribue--whose circulation sometimes surpassed one million--commissioned a survey of women readers; Gosden and Correll's columns turned out to be by far their favorite feature in the Metropolitan Section. (p 56)

Other cross-promotions included Correll and Gosden travelling to the Kentucky Derby and the Indianapolis 500 and having their black alter egos serving as radio correspondents. As Hilmes later notes: "By early 1928, Sam n' Henry had become so popular nationwide through personal appearances, recordings, books, toys, and other ancillary products (such as the "Sam n' Henry" candy bar) that demand for the program exceeded the reach of WGN." (p 84-5)

When the time came to renew their contract with the Tribune, Correll and Gosden also sought to acquire the ability to develop a primitive form of syndication they had been thinking about, later billed a "chainless chain." WGN balked at their demands and so the duo went to the Tribune's cross-town rival, the Chicago Daily News.

Since WGN owned the rights to everything related to Sam n' Henry, Correll and Gosden wanted to keep the same premise of the show but they at least had to change the names of their characters. And so, Amos n' Andy was born. In addition to making minor changes to the storylines, the creators of the show had an opportunity to expand their market. Melvin Ely explains:
Gosden and Correll therefore created what they called a "chainless chain." They wrote Amos n' Andy and recorded the episodes on discs six weeks or more in advance. They then sent copies at no charge to radio stations that would agree to broadcast the show for a month. Thirty or forty stations that sampled the series became paying subscribers after the trial run; six nights a week, interested listeners from Boston to California could now count on hearing the adventures of Amos and Andy. (p 58)
With merchandising spin-offs, personal appearances, and a growing national audience, Amos n' Andy became one of the most popular radio programs on the air. As Bart Andrews and Ahrgus Juilliard note in the introduction to Holy Mackerel!: "Department stores open in the evening piped in the broadcasts so shoppers would not miss and episode. The program was frequently referred to in the Congressional Record." (p. xvi). As their popularity increased, Correll and Gosden caught the eye of a national radio marketer. Ely explains:
Amos n' Andy's triumphs caught the eye of Lord & Thomas, the prestigious advertising agency, and of the National Broadcasting Company. The agency suggested that one of its clients, Pepsodent toothpaste, sponsor the radio series on one of NBC's two national chains....The two performers knew they were bargaining from strength, and they got a rich deal from NBC: $100,000 a year for a fifteen-minute show six nights per week. (p 60)

Correll and Gosden's relationship with NBC lasted from 1929 to 1938, when they switched to CBS and had a new sponsor, Campbell's Soup. Although they endured a number of racial protests throughout their career, Correll and Gosden continued appearing on the radio as the blackface duo (in various program formats) until 1960, making them one of the longest-running comedy teams of all time in addition to being one of the most criticized.