According to the town history at the official website, Eureka is located in "a remote area of the Pacific Northwest." I'm pretty sure I've spied a map while watching the show that indicates it's in Washington state...but of course, that's unofficial information. ;)
(Update: in the 12.07.10 episode "O Little Town", a road sign shown onscreen in the opening minutes (a flashback scene, as the character Sheriff Jack Carter recounts a story to a few snowbound kids in Cafe Diem) partially reads "Eureka Oregon").
im not sure of the town, but i know the state is wisconson
It was announced on July 24, 2009 that the show had been picked up for a 22 episode fourth season, set to air in mid-2010.
in season 11's finale, it is said that springfield is a town in kentucky. that is the only concrete answer given in the history of the show.
New York
lazy town
cafe diem
SyFy's Haven is taped in Nova Scotia, Canada.
The Eureka stockade was a temporary stockade, not a town with any sort of population.
They Are Geniuses
The Eureka Stockade took place in Ballarat.
For the british among us a town called eureka is on sky one on a Tuesday night
The film is called From Within.
im not sure of the town, but i know the state is wisconson
The makeshift defence known as the Eureka Stockade was built in the gold-mining town of Ballarat, in Victoria, Australia.
They are geniuses
I think it's called a "boomtown." A good example is present day Eureka, California. EUREKA!
NORTHERN EXPOSURE