Popular entertainment that happens after dark is called nightlife. In your small town, the nightlife might be all about disco night at the Elks Lodge.
Any social activity you take part in at night can be called nightlife, but the word usually describes things like dancing at clubs, big parties, and live music concerts. If you visit a large city, there is going to be more nightlife available than if you spend the summer in remote Alaska. This word, with its original definition, "habitual nocturnal carousing," dates from the 1850s.