Sully County, South Dakota Demographics 2026

Population Overview

Sully County is located in South Dakota with a total population of 1,526. It is the 63rd most populous county out of 66 in South Dakota. The county encompasses 3 Census-designated places.

Age Demographics

The median age in Sully County is 46.9 years. This is 23% higher than the state median of 38.0 years.

Economy, Income & Housing

The median household income in Sully County is $72,578. This is 3% lower than the state median of $75,081. It is also 10% lower than the national median of $80,734. The poverty rate stands at 6.3%. This is 47% lower than the state poverty rate of 11.9%. The survey records no unemployed residents in Sully County, which reflects the size of the sample rather than a labor market without joblessness. The median home value is $205,400. Housing costs are 20% lower than the state median of $257,400. With a home-value-to-income ratio of just 2.8x, Sully County is one of the most affordable housing markets in the area. 72.8% of occupied housing units are owner-occupied. This homeownership rate is 6% higher than the state average of 68.6%.

Race & Ethnicity

Sully County has a predominantly White (non-Hispanic) population, comprising 86.5% of all residents. Black or African American residents account for 4.5%. The Black or African American population is significantly higher than the state average (4.5% vs 2.1%).

Education

24.1% of residents aged 25 and older hold a bachelor's degree or higher. This is 25% 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 96.1%.

Data Sources & Methodology

All figures for Sully County come from the U.S. Census Bureau's American Community Survey (ACS) 2020–2024 5-Year Estimates, with comparisons drawn against South Dakota and national averages from the same dataset. See our methodology page for how each metric is defined, or data.census.gov for official tables with margins of error.