F. Scott Fitzgerald wrote that Prohibition was a time when, “the parties were bigger,the pace was faster, and the morals were looser.” Hoagy Carmichael wrote that the 1920s came in “with a bang of bad booze, flappers with bare legs, jangled morals and wild weekends.”
Up until the 1920s, knees were kept hidden beneath skirts and petticoats and showing them off would have been scandalous and provocative to say the least .
Back then some women used rouge to highlight and draw attention to their cheeks, although modest women resisted the use of make up and preferred to make the most of ‘natural’ beauty instead.
Flappers, on the other hand, thought of themselves as promiscuous and sexy rebels, and so they rouged their knees to draw attention to them .
Historically Speaking 