The area was first settled in 1836 by John Ferdon. The new settlement was first known as Williamsport after early settler Clark Williams. The community was soon known as Barrington for another settler J. A. Barrington. Again, the community's name was known as Swizzletown. The community received its first post office under the name Greenbush on January 29, 1844, which was named after the township. On May 9, 1867, the post office and community were renamed Eureka, which was the name given by Edward Stark using the word
eureka "as a place where he had found and others would find a fine place for doing business." The post office was discontinued on June 29, 1935. It was ultimately reestablished on September 6, 1949. The post office remains in operation and is located at 7907 North Welling Road in the center of the community. The Eureka Cemetery is located on Hyde Road just south of the center of the community. The cemetery remains active, and its oldest gravesite dates back to 1839. For the
2020 census, Eureka was included as a newly listed
census-designated place, which is included for statistical purposes only. Eureka continues to remain an unincorporated community with no legal autonomy of its own. ==Demographics==