The 9th World Science Fiction Convention, also known as Nolacon I, was held 1–3 September 1951 at the St. Charles Hotel in New Orleans, Louisiana, United States. The chairman was Harry B. Moore. The guest of honor was Fritz Leiber. Total attendance was approximately 190. The at-the-door membership price was US$1, the same price charged from the 1st through the 12th Worldcon
Other pros attending included Robert Bloch, Fredric Brown, Judith Merril, E.E. Smith, L. Sprague de Camp, editor John W. Campbell and fantasy artist Hannes Bok, who did Nolacon's program book cover. Famous fans present included Sam Moskowitz, Wilson Tucker (aka Bob Tucker), Dave Kyle, Roger Sims, Terry Carr, and Lee Hoffman. The latter, editor of the very popular fanzine Quandry, whom everyone assumed was male, turned out to be a young woman, a ‘revelation’ which greatly startled even those who had corresponded with her.
Notable events included world premiere screenings of The Day The Earth Stood Still and When Worlds Collide, plus a continuous two-day-long party in Room 770 at the St. Charles Hotel that became legendary following the convention not only for its duration but for its high quality. Mike Glyer's long-running newszine File 770, named in commemoration of this party, has won the Hugo Award for Best Fanzine a number of times.
Hugo Awards were not presented at this Worldcon as the awards were not proposed until the following year, 1952, with the first Hugos actually presented in 1953 at the 11th World Science Fiction Convention. However, in 2001 at the 59th World Science Fiction Convention held in Philadelphia, a set of Retro Hugo Awards were presented to honor work that would have been Hugo-eligible had the award existed in 1951. A "Certificate of Merit" was presented to representatives of The Day the Earth Stood Still by the Nolacon I chairman, and this was reported on Movietone News at the time.