A small correction: Costco is now headquartered in Issaquah, but they started out in the city of Kirkland. They moved to Issaquah (a 20 minute drive) in 1994, about the time the Kirkland brand was created
I think the first Costco was located south of downtown Seattle, south of the stadiums? Or is it the one that is actually in Kirkland relatively close to the 405?