The OED's Earliest day of 1939 notwithstanding, the time period "blue movie" (ordinarily in quotation marks, as you'd anticipate a newfangled time period to become) appears during the related sense in sources from as early as 1923. Sven Yargs 173k4040 gold badges473473 silver badges829829 bronze badges 2 1 That is https://us.hc6.org/