Why do American high schools host proms?Certain social trends start in the upper classes, then move downward into the societies below them. I think proms are one of these.
The upper class in the 18th-mid-20th C. had 'coming out' parties or 'debut' parties. These were social occasions to mark the adulthood of young women. It was also to advertise -- discreetly -- their availability for marriage. While only one or a few of the young women were the stars of the event, they were joined by other young women, including those who had made their debuts earlier in the season. And men of the same class, of course.
The event was a form of ball, with dancing and dining. It might also include alcoholic punches, but drunkenness was not acceptable. The event could, therefore, also be seen as a filtering mechanism that identified those who couldn't hold their drink. (Not all young women are averse to the bad boys, of course, but that's an entirely different subject!)
As upper-classes were diminished both by poverty and being out-reproduced by the middle class, the event became more common. Imitation played a major role here, as well. As the lower classes couldn't afford the coming out parties -- which could be the second most expensive event in a young woman's life, following only marriage -- they sought and found another occasion: the high school prom(enade). Here were the available and now mature women, introduced to society and eligible men.
Graduation, too, marked a threshold to maturity: the attainment of a certificate that said one was ready to enter the working world. It was its own right of passage.
Debutante balls have fallen into disuse these days, except among certain super-rich groups. They still use it to mark the maturity and availability of young women among their class. It has gotten so expensive, though, that only the super-rich can afford to do it.
Proms call for a certain amount of expenditure -- gowns, flowers, transportation, and apparently also hotel rooms for post-prom parties and/or sex -- but they are attainable.
Proms have also continued their slide toward mass participation. Middle schools are holding proms as well as some elementary schools, though these tend to have simpler parties. The signaling has changed for the pre-pubescent, but they are focusing more on the crossing a threshold aspect than the marriage aspect.
John Burgess accurately details in this thread the origin of proms, though as to Why we have them, the matter is down to economics: The Prom is another Product sold to Consumers--they who replaced the Citizens of a former era.
Like Mother's Day or juvenile Birthday parties, Prom is a concept produced 90% from whole cloth in the Twentieth Century, blatantly to sell goods. Young men and women from poor families are compelled to bedevil themselves for months and take on significant debt so that the assorted purveyors of Prom may themselves make a living. In Prom season, dollars travel around the town's economy like tinkers, visiting many homes: the florist, dressmaker, dry cleaner, chauffeur, bootlegger, shopkeeper, etc.
It's all a complete waste of resource from which one is meant to glean some happy memories prior to undertaking the consistent lifelong drudgery to follow their impending matriculation to the workforce.
Prom thereby enjoys the advantage other examples don't: it is both expensive and pathetic.
As a sophomore in high school, i haven't been to prom, or homecoming for that matter. It's just an excuse for people to spend money on a dress they're only gonna wear for that night, and th men buying corsages for their dates. No one asked me to homecoming (not gonna happen for prom either.)
I don't really see the big deal. And plus, at my school, only the popular people get to be the king and queen of homecoming and prom. I hadn't gotten nominated for homecoming queen yet, I might run for homecoming queen next year.