The major influence on the popularity of the flapper during the 1920s was:
A shift away from the traditional roles of women.
Flappers represented a new ideal of femininity, embracing a more liberated lifestyle that included more social freedom, fashion innovations, and a challenge to conventional gender roles. This shift was partly fueled by the changes in society during and after World War I, where women's contributions in the workforce and their social status began to evolve significantly.