Rise of the pulps
An economic recession in 1893 inspired magazines normally aimed at the middle class that cost 15-25 cents to drop their prices. The success of these magazines inspired Frank A. Munsey, the publisher of Argosy, a boys’ magazine, to transform it into a 192-page magazine full of adult adventure stories. By 1907, Argosy had half a million readers.
Other publishers followed suit and the pulp magazine was born. Pulps took their cues from dime novels, and focused adventure stories on characters such as John Carter of Mars, Tarzan and Zorro, the Masked Avenger.
Hard-boiled noir detective stories were created when readers got tired of the analytical, thinking type of detective which had arisen as a reaction to the action-oriented detectives favored in early dime novels.
The American frontier had been conquered, and so the frontier in pulp fiction moved to outer space and to fictional worlds. Stories taking place in extra-planetary space or in imaginative worlds rose in popularity, creating the science fiction and fantasy that we know today.