Which novel by Edgar Allan Poe is considered the first detective story?

The Edgar Allan Poe work commonly considered the first detective story is The Murders in the Rue Morgue.

Poe published the short story in Graham's Magazine in April 1841. It introduces C. Auguste Dupin, an amateur investigator who uses observation and “ratiocination” to solve the apparently impossible murders of Madame L'Espanaye and her daughter in Paris.

The story established patterns that became central to detective fiction: a brilliant eccentric investigator, a close companion who narrates the case, a police force that misses key clues, and a final explanation that reconstructs the crime. Dupin later returned in The Mystery of Marie Rogêt and The Purloined Letter.

The label is conventional rather than absolute. Earlier works, including E. T. A. Hoffmann's 1819 story “The Scuderi Maid,” are sometimes cited as precursors. Still, Poe's story is widely regarded as the first modern detective story and a foundation of the genre.