Eureka is a city in Humboldt County, northern California. The U.S. Census Bureau reported a population of 26,512[1] in the 2020 census. The urban area has a size of 37.4 km².
The urban landscape is characterized by deep furrow-like valleys called “gullies” and redwood forest. Well-known features of the town are the many Victorian houses and the Pulp Mill. On October 15, 1991, Old Town Eureka was added to the National Register of Historic Places as a Historic District.