Popularisation
Several studio-made films in the 1960s popularized the use of split screen. They include "Indiscreet (1958), John Frankenheimer's Grand Prix (1966), Richard Fleischer's The Boston Strangler (1968), Norman Jewison's The Thomas Crown Affair (1968), Airport (1970), Woodstock (1970), Carrie (1976) and More American Graffiti (1979).
In "Indiscreet" the technique was famously used to bypass the censors and allow Cary Grant and Ingrid Bergman to be in bed together, and even to appear to pat her on the bottom.
Read more about this topic: Split Screen (filmmaking)