War may be happening in Europe, but for the moment it's still the Jazz Age in the USA. Newspapers are sold by young, possibly disabled, boys on the street. Businesses are run by Corrupt Corporate Executives, and while the well-off enjoy nightclubs, the after-effects of The Great Depression still overshadow the lives of the poor.
The Trope Namer story suggests it is "1938, maybe '39, maybe even 1940" and calls this "eighteen months or so before the start of World War II". Hah! Try telling a European that!
Prohibition is probably over, but the power that The Mob gained in that period means they run many of the bars and clubs. The police may be trustworthy or they may be corrupt. They may very well be brutal.
Differs from the Genteel Interbellum Setting, with which it overlaps with the last years of, in being more urban, more cynical, more violent, more temporally specific (in contrast to the Genteel Interbellum Setting's chronological indeterminacy, Chandler American Time is confined to the very tail end of the epoch) and geographically confined to the USA.
Everyone wears hats.
Crimes are committed by the kinds of people who commit crimes in real life, and by realistic methods. Shootings by ex-gangsters trying to prevent their past being exposed? Yes. Chief of French police chopping a millionaire's head off, then switching it with another head he pinched from the guillotine, all because the policeman was an atheist and wanted to stop the millionaire leaving his fortune to the church? No. (That's the actual solution of Father Brown: The Secret Garden!)
Since elaborate but silly murder methods are out, any crime must have many suspects and incredibly tangled motives in order to be puzzling. This is usually helped along by having the poor sap that kicks off the plot being a bit of an Asshole Victim.
- Trope Namer: the short story Umney's Last Case by Stephen King.
- The differences from the Genteel Interbellum Setting are pretty much the whole point of Raymond Chandler's essay The Simple Art of Murder.
- Pretty much any pastiche or parody of Film Noir or the Golden Age of comics.
- Many of Raymond Chandler's Philip Marlowe stories.
- The standard timeframe of Two-Fisted Tales, such as Indiana Jones or The Rocketeer.
- The early Nero Wolfe mysteries are set in this time period. When the author resumed writing them after the Second World War, he used a form of Comic-Book Time to keep the characters contemporary for the time of publication.
- Fantastic Beasts and Where to Find Them is set in New York, 1926, and manages to get some of the tropes associated with this in, including a scene in a goblin-run nightclub/speakeasy, complete with a house-elf crooner performing onstage.