As Reno in 2011 is now running apparently unopposed, this has led to people speculating that "this will be the smallest city to every host a Worldcon." Well, that all depends on how you define it, I think. "By Mayoral Proclamation," the 1958 Worldcon was in South Gate, California, although it was physically in Los Angeles. I think most people probably count this as "metropolitan area" rather than the technical city in which the convention was held, so, for instance, all five Bay Area Worldcons are all in the same "place" for this purpose, so the fact that Berkeley only had 114,091 in 1970 (the 1968 Worldcon was in the Claremont Hotel
on the Oakland-Berkeley boundary; the hotel's entrance is in Berkeley but most of the hotel was in Oakland) isn't relevant.
A little searching finds that the Reno-Sparks Metropolitan Statistical Area
had 410,272 people in 2007. I thought that possibly Brighton
, with a listed population at about the same time of 251,400, might beat it; however, you have to use comparable terms. An MSA is the county (or counties) in which the named cities are located (in Reno-Sparks' case that's Storey and Washoe counties, Nevada). The equivalent for Brighton is East Sussex
, which has a claimed population of 752,900. Winnipeg
might also be in the running -- its metro area is listed as 694,668.
Maybe other people can look over the Long List of Worldcons
and do more research, but after my first pass, it does appear that the 2011 Worldcon is probably going to be in the smallest metropolitan area to ever host a Worldcon. The facilities there certainly aren't small, however. I'd be more comfortable if there was one more large hotel directly on site rather than a kilometer away, but there's plenty of convention center space; more than we'll need, I'm sure.