In the United States, I’d probably name Oregon City, the famous end of the Oregon Trail and the first city founded west of the Rocky Mountains during the pioneer era. Its population is only 37,000.
Here in Illinois is Woodstock, at ~25,600 (2020 per Wikipedia). It was the town where Groundhog Day was filmed. There’s even some small road signs here and there mentioning it for the rare tourist who comes to see it. Smallest place in the state I can think of, though there’s smaller towns that have been used for movies.
Some upcoming off-brand Hallmark x-mas movie will feature local tourist trap town Long Grove IL, pop ~ 8,300 (2020 per Wikipedia). The director grew up near there so knew about it and thought it’d be perfect for his movie.