In 1990, the Grateful Dead added a third show to what was previously scheduled as a two-night run. The venue for this third show was only half full due to the late scheduling of the show. What run of shows (venue & dates) was this, and why was the venue only half full?

Of the first ten correct answers
(Oct. 30, 31 and Nov. 1, 1990, Wembley Arena, London, England. The venue was only half full for the final show because many Americans who had gone to Europe for the tour had already scheduled their return flights to the US on Nov 1.), Tom B. was chosen at random and won a Furthur 2010 Radio City poster.