Proms started to happen in America initially in the past, and the trend is spreading. It may be a celebration when you finish for a college or school in the form of moving out party prior to embarking on the next stages of life.
Initially consider the 63 only for college as a celebration that the child gets a responsible adult. This being said they will also be in lower aged schools too. This can be described as cause for a great celebration and definitely will usually be celebrated accompanied by a large formal dance. Normally the men will be dressed in a suit of tuxedo and then the women will be in a prom dress.
A a number of other countries across the globe also follow this tradition now. The US plus the EU have tight bonds therefore it is not a surprise to discover the European countries following suit.
The UK has become quite big on proms, as they are Germany and Spain. A substantial amount of people in USA speak Spanish there is are some strong links having something made not surprising to see they can be big on proms. Some in this is from South American influences whilst some from the Spanish who moved to the US many years ago.
In many Spanish schools as well as in higher education you will see more students partaking in prom celebrations. The women in his or her vestidos de fiesta and then the men in their normal suits, simply as in the US.