In Scholastic chess in the United States, Wikipedia tells us,
Normally the major tournaments (high school, junior high school, elementary/primary) are held in different locations at different times, to allow participation in multiple events. However, beginning in 1997, there has been a single event known as the Supernationals where all events are held in one place simultaneously.
Of the two mega-scholastic events initiated in the 1990s, Chessathons and Supernationals, only the Supernationals have survived into the 2010s. The First USCF Chessathon was held in 1992, and the first Supernationals in 1997.
The cover of the July 1997 issue of Chess Life (CL), shown on the left, called the event the 'Woodstock of Chess'. Held on 25-27 April in Knoxville, Tennessee, there were four separate tournaments, to which CL devoted four pages just to list the winners. The National High School (K-12) event was won by Harutyan Akopian (Akopyan; not to be confused with Armenian GM Vladimir Akopian), while the National Primary (K-3) event went to nine year old Hikaru Nakamura.
The 'Woodstock of Chess' moniker was conferred by CL Editor Glenn Petersen in his report on the Supernationals, and not just for the event's size and historical significance.
Thousands of cars, vans, traffic jams (the main road into Knoxville was under construction) ... bodies to the left, bodies to the right, no place to sit, chessboards and sets, and arms and legs covered every available inch of floor space in the lobby, in the atrium, in the skittles rooms, in the hallways, masses of humanity pressed together ... rain [...] 4235 children (and probably an equal number of parents and coaches) from 48 states, were part of history in the making.
The event was conceived and awarded in 1994.
The recently held U.S. Open in Chicago, Illinois was a great event but it was more than a chess tournament. It was the site for the annual Delegates’ Meetings, workshops, and Policy Board Meetings. [...] The Policy Board awarded an option for the 1997 "Supernational" Scholastic to the TN Chess Association with details to be worked out with the Business Office.
Unofficial Summary of the USCF Policy Board and Delegates' Meetings; August 10-16, 1994 by Rachel Lieberman [rec.games.chess]
There was some controversy at the time because the award was made without a competitive bidding process. The event was the responsibility of the USCF Scholastic Chess Director, whose overall tasks were listed in another rgc post.
5. Supervises and coordinates major scholastic events, avoids scheduling conflicts, and acts as USCF’s scholastic representative on site as appropriate for the following national tournaments:
* National Elementary
* National Junior High
* National High School
* Super Nationals
* National Scholastic K-12 Grade
* Junior Chess Congress (all regions)
* National Scholastic Action (aka All America Cup)
* Pan American Intercollegiate
* U.S. Junior Open
Scholastic Director’s Job Responsibilities [April 1997; rec.games.chess]
Beatriz Marinello was the USCF Scholastic Director at the time of the 1997 Supernationals. She later became the USCF President and a key figure in the FIDE hierarchy.
The second of the Supernationals was held in 2001. Other events followed every four years -- 2005, 2009, and 2013 -- making five events to date.