Eureka is a city in and the county seat of Greenwood County, Kansas, United States. As of the 2010 census, the city population was 2,633.
Eureka got its name when an early pioneer shouted "Eureka!" after discovering a spring of water, now known as the Fall River.
Eureka is located at 37°49′22″N 96°17′22″W / 37.82278°N 96.28944°W / 37.82278; -96.28944 (37.822745, -96.289583). According to the United States Census Bureau, the city has a total area of 2.0 square miles (5.1 km²), all of it land.