The original play was based on Maurine Dallas Watkins' experiences reporting on murder trials in Chicago in the 1920s. In particular, it was based on two trials.
One was that of Beulah Annan (who was the basis for Roxie). She was accused of murdering Harry Kalstedt, her lover. She claimed that he tried to rape her and she shot him in self defense. The police concluded that he tried to leave her and she shot him out of jealousy. Her husband pooled as much money as he could to get her the best lawyers in Chicago. Beulah went to trial in 1924 but was acquitted. Immediately after the trial, she divorced her husband claiming that he was "too slow".
Another trial that figured into Watkins' play was that of Belva Gaertner (the basis for Velma). She shot and killed her lover, Walter Law. He was found in the front seat of Belva's car. She was later found at her apartment with blood-soaked clothes on the floor. She said that she was drunk and couldn't remember what happened. She went to trial. Her defense was that Law had killed himself. Belva was acquitted.
On February 3, 1956 — yes, 1956 — it was reported in the New York Times that the producing team of Robert Fryer and Lawrence had asked Gwen Verdon, then starring in Damn Yankees, if there was anything she was particulaly interested in doing after her Damn Yankees contract expired on December 1 of that year. She told them that she was interested in playing Roxie Hart in a musical version of the play Chicago. She had seen the film version, and the role intrigued her. Fryer and Carr optioned the play and set about trying to find the right adapter and songwriter.
According to a Playbill article dated September 16, 2008, there have been 10 National Companies for the show since 1997. If the two Non-Equity tours are counted, then there are 8 that our research has turned up with.