Day Of The Underwear, New York City, United States

Women's bloomers became much shorter and stockings covered the legs instead. The shorter bloomers became looser and less supportive as the boyish flapper look came into fashion. By the end of the decade, they came to be known as "step-ins", very much like modern panties but with wider legs. They were worn for the increased flexibility they afforded.
As dancing became a favourite pastime of young flappers, the garter belt was invented to keep stockings from falling. The increased sexual awareness of the flapper also made underwear sexier than ever before. It was the flappers who ushered in the era of lingerie.
A Russian immigrant named Ida Rosenthal further developed the brassiere in this decade when she introduced modern cup sizes in 1928 for her company, Maidenform.