- The Redjac entity, incarnated as "Jack the Ripper", murders seven women in Shanghai, China on Earth. (TOS: "Wolf in the Fold")
- Carl Jung develops his active imagination technique, although he doesn't realize Native Americans have been performing vision quests for centuries prior. (VOY: "The Cloud")
- At the Roxy Theater in New York City, the comic duo of Burns and Allen first performed a classic comedy routine. At the close of the show, Burns would say, "Say good night, Gracie", and Gracie replied, "Good night, Gracie". (TNG: "The Outrageous Okona")
- The Palace Theater is built in Chicago. (VOY: "Repression")
- According to the script for TNG: "The Big Goodbye", Lieutenant McNary, a character in the Dixon Hill series, was assigned to the Homicide Squad in the San Francisco Police Department's Precinct 12.