Eureka is a city located in St. Louis County, Missouri, United States, adjacent to the cities of Wildwood and Pacific, along Interstate 44. It is in the extreme southwest of the Greater St. Louis metro area. As of the 2010 census, the city had a population of 10,189. Since 1971, Eureka has been known as the home of the amusement park Six Flags St. Louis.
The village of Eureka was platted in 1858 along the route of the Pacific Railroad. By 1890, the village consisted of about 100 homes. According to the Eureka Chamber of Commerce, railroad workers while clearing the way for the track and the next railroad camp saw Eureka, level land with little to clear, and declared, "Eureka!" Greek meaning "I have found it." Thus, Eureka was founded.