| Official Name: | Eureka Township |
| Settlement Type: | Township |
| Subdivision Type: | Country |
| Subdivision Type1: | State |
| Subdivision Type2: | County |
| Subdivision Name2: | Adair |
| Area Total Km2: | 92.19 |
| Area Land Km2: | 92.06 |
| Area Water Km2: | 0.13 |
| Unit Pref: | Imperial |
| Area Total Sq Mi: | 35.59 |
| Area Land Sq Mi: | 35.54 |
| Area Water Sq Mi: | 0.05 |
| Area Water Percent: | 0.14 |
| Population As Of: | 2020 |
| Population Total: | 101 |
| Population Density Km2: | 1.0 |
| Population Density Sq Mi: | 2.5 |
| Elevation M: | 398 |
| Elevation Ft: | 1306 |
| Coordinates: | 41.3747°N -94.6439°W |
| Timezone: | CST |
| Utc Offset: | -6 |
| Timezone Dst: | CDT |
| Utc Offset Dst: | -5 |
| Postal Code Type: | ZIP codes |
| Postal Code: | 50846, 50849 |
| Blank Name: | GNIS feature ID |
| Blank Info: | 0467800 |
Eureka Township is one of the seventeen townships of Adair County, Iowa, United States. At the 2020 census, its population was 101.[1]
Eureka Township was organized in 1870.[2] "Eureka!" is said to have exclaimed by an early settler when he discovered coal within the township borders.[3] It was served by Berea post office from 1894 to 1908,[4] named after the Ancient Greek city of Berea.[5]
According to the United States Census Bureau, Eureka Township covers an area of 35.59 square miles (92.19 square kilometers); of this, 0.05 square miles (0.13 square kilometers) or 0.14 percent is water.
The township contains one cemetery, Eureka.