"The Other Side of the Fog" is a short-story included in the 1960 self-published magazine People, Places and Things.
The story concerns a mysterious fog that serves as a door between dimensions. Pete Jacobs involuntarily travels through the fog into the future (the year 2007) and eventually to a world inhabited by dinosaurs. Helpless, he wanders from one dimension to the next, searching for his own.
The use of a mysterious fog with otherworldly properties was revisited by King in "The Mist," while the idea of a wanderer traveling through alternate dimensions searching for his original universe presages the television series Sliders.