CLUES, a scholarly journal devoted to detective fiction in all its forms, has announced plans for an issue on "the Girl Sleuth." See the call for papers at the Children's Literature Association wikisite.
Stories about female detectives have been marketed to young readers for over a century. The Old Sleuth, one of the most popular dime-novel detectives, had an assistant named Maggie Everett, who specialized in trailing criminals; in case she was attacked, she carried a club in her purse. Laura Keen, the Queen of Detectives, went further: she used pistols and a knife in her own 1892 adventure. These and other dime-novel female detectives were all adults, as far as I can tell.
The creation of the girl detective, like that of the boy detective, seems to have come in the early twentieth century. It probably started with one-offs in standard girls' series, like Marion Marlowe's Skill; or A Week as a Private Detective, by "Grace Shirley" in 1900. One pioneer in writing series about teenaged "girl sleuths" was L. Frank Baum, who published Mary Louise under the pseudonym Edith Van Dyne in 1916. That book's second protagonist, Josie O'Gorman, is a policeman's daughter who goes undercover. Toward the end we read:
"It's good to see you again, Josie," said O'Gorman, as they seated themselves on the bench. "How do you like being a sleuth?"Despite not being a WASP, Josie grew increasingly important in the Mary Louise series. Under second writer Emma Speed Sampson, she took it over entirely.
"Really, Daddy," she replied, "it has been no end of a lark. I'm dead sick of washing other folks' dishes, I confess, but the fun I've had has more than made up for the hard work. . . . I'm patting myself on the back, Dad, because you trained me and I want to prove myself a credit to your training."
In 1917 Baum even referred to the young heroines of The Lost Princess of Oz as "girl detectives." That book's not really a mystery, but I had to say something in this entry about fantasy, hadn't I?
Click on the thumbnail cover of Old Sleuth Weekly above for a bigger, better picture of "Wild Myra" punching out kidnappers about 1910. It comes from the Stanford University library's online exhibit of dime novels, penny dreadfuls, and popular literature of other currency, which is well worth a browse. The University of Minnesota library offers a checklist of girls' series.