By 1875, Eureka had a post office. The original mill was closed (reasons unknown) but to replace it, the Gold Prince Mill from Animas Forks was deconstructed and moved to the Eureka townsite to become the Sunnyside mill. In 1896, Eureka was connected to the Denver and Rio Grande Railroad via the Silverton Northern Railroad. Although the community grew steadily — not like a boomtown — it quickly declined after 1939, when the Sunnyside Mill closed for the last time. Today, the original townsite gravel roads remain, and debris litters the area. The only remaining structure is the Eureka jail, which has been restored. Foundations remain of the Sunnyside mill.