Tea dances are a common cultural reference in early 20th century fiction as a staple of genteel society, where people normally attend these receptions while visiting resort towns (like Brighton or the Hamptons). One example can be seen in the 1925 hit Broadway musical "No, No, Nanette." A tea dance provides the setting for the plot's climax when the main characters travel to Atlantic City [the same musical also features the famous song "Tea for Two" which is sung prior to this scene].
In the United States, the term has been broadened to refer to any casual afternoon dance event. An infamous example was the 1981 Hyatt Regency walkway collapse in Kansas City, Missouri, that occurred during an afternoon dance which killed 114 people and injured 200. The incident inspired the song "Rockin' at the T-Dance" by The Rainmakers.
This term – sometimes spelled T-dance – is also used within gay culture to designate similar dances: particularly those held on weekends (especially Sunday evenings) in night clubs, or at the end of the day at gay resorts (usually beside a pool). A live DJ typically plays recorded club music at these tea dances. It originated at the Blue Whale hotel/club/restaurant on Fire Island, NY, as a way to entice visitors to spend additional time (and money) before taking the Ferry back to the mainland to prepare for their workweek.