Eureka (yōrēˈkə) [key], port city (1990 pop. 27,025), seat of Humboldt co., NW Calif., on Humboldt Bay; inc. 1856. Lumbering, fishing, tourism, and dairying are all important to its economy. A 40-acre (16-hectare) redwood park is in the city, and to the southeast is the Headwaters Forest, the largest remaining stand of virgin redwoods. In Eureka is the College of the Redwoods; Humboldt State Univ. is nearby.