(1) Eastercon 2007
The Adelphi Hotel, in spite of (because of?) having been the site of multiple previous Eastercons was not considered safe by fans and Convoy had very low membership. They announced that they needed a substantial increase in memberships and and the committee had committed itself to getting further assurances about Adelphi Hotel security in order to continue. One or both failed to materialize, and the cancellation was announced on 31 October.
It was replaced by the low-key Contemplation.
(2) A Buscon
in 1977 Lunacon 20 and Balticon 11 were both on Easter weekend Erwin S. Strauss announced ConVoy as a "Science fiction convention on wheels. A mobile lounge will shuttle between LunaCon and BaltiCon all weekend. It will even pick you up at your home, and drop you off back there, if you live near the route from Washington DC to New York City… Our van will be completely outfitted for partying — thick carpeting on the floor and walls, special lighting and ventilation, refreshments, entertainment, rest room — the works! It will have to be seen to be believed. And all this costs little more than the round-trip bus or train fare to just one of the two conventions. Your membership entitled you to ride as much as you want on all three days — for example, you can go to one con Friday night, move over to the other con Saturday afternoon, and go home Sunday night."
See also Buscon.