Eureka, South Dakota Demographics & Population 2026

A note before these figures: with a population of 778, Eureka's ACS estimates come from a small number of survey responses and carry wide margins of error. Individual percentages below — particularly rates that round to 0% or 100% — are approximations, not precise measurements. See data.census.gov for the published margins of error.

Population Overview

Eureka is a small community located in South Dakota, within McPherson County. The total population is 778. It ranks as the 104th most populous out of 439 Census-designated places in South Dakota.

Age Demographics

The median age in Eureka is 63.1 years. This is 66% higher than the state median of 38.0 years. Only 13.8% of residents are under 18, indicating fewer families with children. 24.0% of residents are 75 or older, suggesting a significant retirement-age population with implications for healthcare services and senior housing.

Economy, Income & Housing

The median household income in Eureka is $47,583. This is 37% lower than the state median of $75,081. It is also 41% lower than the national median of $80,734. The poverty rate stands at 15.2%. This is 27% higher than the state poverty rate of 11.9%. The unemployment rate is 0.3%. This is 89% lower than the state rate of 2.9%. The median home value is $78,200. Housing costs are 70% lower than the state median of $257,400. With a home-value-to-income ratio of just 1.6x, Eureka is one of the most affordable housing markets in the area. 81.8% of occupied housing units are owner-occupied. This homeownership rate is 19% higher than the state average of 68.6%.

Race & Ethnicity

Eureka has a predominantly White (non-Hispanic) population, comprising 95.1% of all residents. Hispanic or Latino residents account for 0.3%. The Hispanic or Latino population (0.3%) is well below the state average of 4.8%.

Education

21.9% of residents aged 25 and older hold a bachelor's degree or higher. This is 31% lower than the state rate of 31.9%. Nationally, 35.7% of adults hold at least a bachelor's degree. The high school graduation rate (or equivalent) is 81.2%.

Data Sources & Methodology

All demographic data for Eureka, South Dakota is sourced from the U.S. Census Bureau's American Community Survey (ACS) 2020–2024 5-Year Estimates. The ACS collects data from approximately 3.5 million households annually and pools five years of responses so that even small communities can be measured, though the margin of error widens as the population falls. Comparisons are made against South Dakota state averages and national averages calculated from the same dataset. Rankings reflect the city's position among all 439 Census-designated places in South Dakota. Read more about how these figures are produced on our methodology page, or visit data.census.gov for official data.