They gathered fans from all countries, founding there the opportunity to meet old pen-friends (no Internet at that time), buy rare memorabilias, listen to rare music and watch video on large screens. Sometimes, as in New York, an impersonator contest was organized.
Here are some documents.

"Dylan Revisited 79", Manchester, UK

"Dylan Revisited", 1980, Manchester, UK (quiz list).

"Bob Dylan Festival 1987", 5 & 6 June 1987, Taverne Bauernhof, Michelstetten, Austria.

   "The Circus Is In Town", flyer (front and back) for the Dylan Convention “Mixed up confusion ‘87” organized on 7th and 8th November 1987 in Chicago, Ill. by The Creatures Void Of Form.

"Million Dollar Bash" booklet, Manchester, UK, 5 & 6 Nov 1988

same, flyer

same, pamphlet with the order form.

"Days Of 49", Sachas Hotel, Manchester, 25-27 May 1990

same, 4 pages leaflet giving practical informations for the reunion.

flyer       "Hard Times In New York Town", 50th Birthday Celebration, New York 24-26 May 1991, New York Skyline Hotel: card cover containing 8 pages outlining the guests speakers and events taking place to mark Bob's 50th birthday celebration

2-4 April 1993, "Down Along The Cove", in Seattle, Wa., USA

1994, Flyer for "Bringing It All Back Home" in Manchester 20-21 May.

1996, "Swedish Dylan Convention", organised by Lars Holm.