Actually, the 20th World Science Fiction Convention in Chicago (1962) was informally known as Chicon III. The switch from Roman numerals to Arabic comes about as the numbers increase. In those old days, the use of the annual number (such as the 20th Worldcon) was much more prevalent. The nickname was an informal, handy reference. Nowadays, fifty years after it all began, many fans don't pay any attention to the con's number. By the way, do you have to think twice as to what Noreascon this is and just what Worldcon number it represents?
The Chicago site was the Pick-Congress Hotel, being renovated and looking for business. Its willingness to give convention rates of $7 single and $13 double (suites $25, parking 35¢ a day, and banquet prices at $5.75 and $6.25) (real bargains for sf fans), helped win the bid for another Chicon. (Membership $3 attending, $2 supporting — Ten years earlier at Chicon II the membership was one dollar.)
Chicon III had the usual programming mixture, stressing, however, a main track of lectures and speeches by prominent pros in sf and science (including NASA). (Considering fandom's feuding record, an appropriate program was an authoritative "Science Fiction, Mental Illness, and the Law.") With Bob Tucker (the annual awards banquet MC), Bob Bloch, and Isaac Asimov featured there was plenty of fun and humor. The "Auction Bloch" (selling an hour of a "celebrity's" time to benefit TAFF) continued, now offering a genuine editor.
Fandom was everywhere represented. The entire convention committee joined the N3F (the National Fantasy Fan Federation, which for so many years was the fraternal bond for the true fans.) The N3F was considered a working partner with the con committee, running a Coffee and Cookie Room for basic fannish hospitality. Project Art Show aka Fan Art Show, with Bjo Trimble as usual, had a new wrinkle, a Photo Salon to exhibit work. The Art Show was evolving from an exhibition just for amateurs to one of art by professionals, too. Many a successful pro has come from the amateur ranks through this show. (Incidentally, the popular artist Ed Emsh (Emshwiller), the multiple Hugo winner, brought some of his 16 mm films for a showing of his award-winning visual art-and-camera techniques.)
The auction was still an important means for financing any convention. This year was a good one because donations came not just from the commercial sources but from collectors and fans. Besides artwork from the top artists of the past and present, there were new books, rare books and magazines, manuscripts of all kinds, rare fan material, and many other unusual items. Diligent efforts brought in quantities of remarkably high-quality collectibles, many from celebrated sources (e.g., Charles Shultz, Al Capp, Rod Serling, etc.).
The costume party was given the fancy name of "The Hell-Fire Club Masquerade Ball." It actually was a "ball" because a professional orchestra was hired for playing during the "grand march," to be followed by music for dancing. The costume parade very often had been identified as "a masquerade," which, in fact, it never was. Judging was done rather quickly during the parade. (Was Margaret Brundge, the legendary Weird Tales cover artist of the 1930s, really a judge as claimed? Her raffled painting at Seacon in 1961 was the first actual contribution to Chicon.) This time Ruth and I joined with three others as Flash Gordon adventure characters for the "Best Group" category. We won the prize. Steve and Virginia Schultheis and Jock Root were Prince Barin, Princess Aura, and Dr. Zarkov. Ruth was Princess Azura of the Kingdom of the Blue Witch and I was Azura's father, the Emperor Ming the Merciless. What makes this noteworthy is that I was in the first ever costume contest (Worldcon number two in Chicago, 1940) and won a huge cover painting from Amazing Stories — costumed as Ming the Merciless. Incidentally, Forry Ackerman is responsible for starting the costuming custom when he came to Nycon (1939) in his Things-to-Come Cabal cloak outfit. He went out to the World's Fair in that spectacular thing and publicized Nycon by stepping up to the microphone on a platform for visitors from foreign lands and addressing them in Esperanto. He told them he was a time traveler from the future — so strongly was the then "shy, introverted tongue-tied kid" motivated by the amazing-wonder-Gernsback power of "scientifiction."