| Official Name: | Eureka, Texas |
| Settlement Type: | City |
| Mapsize: | 250px |
| Image Map1: | Navarro County Eureka.svg |
| Mapsize1: | 250px |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Texas |
| Subdivision Type2: | County |
| Subdivision Name2: | Navarro |
| Unit Pref: | Imperial |
| Area Footnotes: | [1] |
| Area Total Km2: | 6.37 |
| Area Land Km2: | 6.19 |
| Area Water Km2: | 0.18 |
| Area Total Sq Mi: | 2.46 |
| Area Land Sq Mi: | 2.39 |
| Area Water Sq Mi: | 0.07 |
| Population As Of: | 2020 |
| Population Total: | 313 |
| Population Density Sq Mi: | auto |
| Population Density Km2: | auto |
| Timezone: | Central (CST) |
| Utc Offset: | -6 |
| Timezone Dst: | CDT |
| Utc Offset Dst: | -5 |
| Elevation Ft: | 341 |
| Coordinates: | 32.0006°N -96.2619°W |
| Blank Name: | FIPS code |
| Blank Info: | 48-24816[2] |
| Blank1 Name: | GNIS feature ID |
| Blank1 Info: | 2410464 |
Eureka is a city in Navarro County, Texas, United States. The population was 313 at the 2020 census.
The settlement developed around a log schoolhouse known as Dunn's School just before the Civil War. In 1870, residents applied for a post office, and at a Grange meeting decided on the name Eureka. That same year, a post office was opened in the home of P. Anderson, and within a few years a small town grew up there. By 1885, Eureka reported several steam gristmills and cotton gins, two churches, a district school, and an estimated population of twenty-five.
According to the United States Census Bureau, the city has a total area of 2.4sqmi, of which 2.3sqmi is land and 0.1sqmi (3.33%) is water.
As of the census of 2000, there were 340 people, 122 households, and 101 families residing in the city. The population density was 146.7sp=usNaNsp=us. There were 143 housing units at an average density of 61.7sp=usNaNsp=us. The racial makeup of the city was 95.88% White, 2.35% African American, 0.29% from other races, and 1.47% from two or more races. Hispanic or Latino of any race were 0.29% of the population.
There were 122 households, out of which 39.3% had children under the age of 18 living with them, 68.9% were married couples living together, 9.0% had a female householder with no husband present, and 17.2% were non-families. 13.9% of all households were made up of individuals, and 10.7% had someone living alone who was 65 years of age or older. The average household size was 2.79 and the average family size was 3.06.
In the city, the population was spread out, with 30.0% under the age of 18, 6.2% from 18 to 24, 27.4% from 25 to 44, 23.5% from 45 to 64, and 12.9% who were 65 years of age or older. The median age was 36 years. For every 100 females, there were 112.5 males. For every 100 females age 18 and over, there were 101.7 males.
The median income for a household in the city was $45,000, and the median income for a family was $46,667. Males had a median income of $32,500 versus $22,031 for females. The per capita income for the city was $15,188. About 4.6% of families and 6.1% of the population were below the poverty line, including none of those under age 18 and 29.5% of those age 65 or over.
The City of Eureka is served by the Mildred Independent School District.