The 1st World Science Fiction Convention (Worldcon) was held on 2–4 July 1939 in the Caravan Hall in New York City, United States, in conjunction with the New York World's Fair, which was themed as "The World of Tomorrow". It was later retroactively named "NyCon I" by Forrest J Ackerman. The convention was chaired by Sam Moskowitz. Along with Moskowitz, other organizers were and .