Apologies if this question is a bit out of bounds for this sub or focuses on, for lack of a better term, low-brow material. I've been curious as to why the early twentieth century, mainly 1920s-1940s pop action fiction in America, started having action heroines, i.e., female heroic characters engaging in combat as well physical fights/gun fights. For example, in the 1920s, the first written Buck Rogers story has female soldiers, not to mention plenty of pulp fiction heroines and early comic book superheroines. I'm trying to figure out why did early twentieth-century American writers start writing about these characters when nineteenth-century writers rarely, if ever, did? What changed in American society or pop culture at this type to instigate the emergence of these types of characters during this time period? Any information, theories, or resources would be appreciated.