County · South Dakota
Sully County, South Dakota
Sully County, South Dakota. Sully County had 1,479 residents in 2025 by the Census Bureau's estimate, up 2.2% since 2020, slower than South Dakota (+5.5%). It holds 3 places (2 cities, villages and boroughs and 1 census-designated) and 1 census tract. GEOID 46119.
Residents, July 2025 estimate
1,479
Census Bureau estimate (no margin published)
2020 Census count: 1,446 · ACS 2020-2024: 1,526 ±127
Median household income
$72,578
±$6,950 (90% margin)
South Dakota: $75,081
Median home value
$205,400
±$32,262 (90% margin)
South Dakota: $257,400
Median gross rent
$842
±$206 (90% margin)
South Dakota: $946
How many people live in Sully County, and is it growing?
The 2020 Census counted 1,446 residents in Sully County. The Census Bureau estimates 1,479 for July 1, 2025, up 2.2% since 2020, slower than South Dakota (+5.5%). The 2020-2024 American Community Survey puts the population at 1,526 over 1,007 square miles of land.
| Measure | Sully County | South Dakota | Change since 2015-2019 |
|---|---|---|---|
| Total population | 1,526±127 | 907,428 | +221 |
| Households | 637±60 | 365,544 | no clear change |
| Average household size | 2.39±0.23 | 2.39 | no clear change |
| Housing units | 934±52 | 408,584 | +120 |
Sully County's population since 2000
From 1,556 in 2000 to 1,479 in 2025: down 4.9%. The 2000, 2010 and 2020 figures are census counts. The 2005 figure is the Census Bureau's intercensal estimate, revised to fit the 2000 and 2010 counts and drawn on 2010 boundaries; 2015 and 2025 are July 1 estimates made from the census before them.
Source: The 2000, 2010 and 2020 Census counts and the Census Bureau's population estimates (intercensal 2000-2010, Vintage 2020, Vintage 2025) · Census population estimates
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); PEP Vintage 2025 (CO-EST2025); 2020 Census · Check it at data.census.gov
What cities and towns are in Sully County?
Sully County holds 3 places: 2 cities, villages and boroughs (incorporated places) and 1 census-designated place. The largest is Onida with 640 residents (2025 estimate). Places that cross a county line are listed with the share of their 2020 residents who live in this county.
| Onida | 666 | $70,000 |
|---|---|---|
| AgarGEOID 4600460 | 68 | not published |
| Cow CreekGEOID 4614320 | 52 | $112,778 |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); 2020 place-by-county parts · Check it at data.census.gov
Who lives in Sully County?
The median resident of Sully County is 46.9 years old; 22.0% are under 18 and 23.1% are 65 or older. The largest group is non-Hispanic white residents at 86.5%, then non-Hispanic residents of two or more races at 4.7%.
| Measure | Sully County | South Dakota | Change since 2015-2019 |
|---|---|---|---|
| Median age | 46.9±3.3 | 38.0 | no clear change |
| Under 18 years | 22.0%±4.9 pts | 24.2% | – |
| 65 years and over | 23.1%±3.2 pts | 18.0% | – |
| Hispanic or Latino (any race) | 0.0%±1.6 pts | 4.8% | – |
| White alone, not Hispanic | 86.5%±3.6 pts | 79.8% | −9.5 pts |
| Black or African American alone, not Hispanic | 4.5%±4.6 pts | 2.1% | – |
| Asian alone, not Hispanic | 0.0%±1.6 pts | 1.4% | – |
| American Indian and Alaska Native alone, not Hispanic | 3.9%±4.1 pts | 7.1% | – |
| Native Hawaiian and Other Pacific Islander alone, not Hispanic | 0.0%±1.6 pts | 0.0% | – |
| Two or more races, not Hispanic | 4.7%±3.1 pts | 4.4% | – |
| Some other race alone, not Hispanic | 0.4%±0.5 pts | 0.3% | – |
| Born outside the United States | 4.8%±4.6 pts | 4.0% | – |
| Speak a language other than English at home (age 5+) | 5.7%±4.8 pts | 7.1% | – |
| Civilian veterans (age 18+) | 3.4%±1.7 pts | 7.9% | – |
| With a disability | 10.1%±2.8 pts | 12.5% | – |
| No health insurance coverage | 6.6%±4.9 pts | 9.0% | – |
| High school graduate or higher (age 25+) | 96.1%±1.8 pts | 93.2% | – |
| Bachelor's degree or higher (age 25+) | 24.1%±5.5 pts | 31.9% | no clear change |
| Graduate or professional degree (age 25+) | 5.5%±2.6 pts | 10.0% | – |
| Moved from another state in the past year | 1.8%±1.3 pts | 3.2% | – |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profiles DP02, DP05) · Check it at data.census.gov
What do households in Sully County earn?
Half of Sully County's 637 households earn less than $72,578 a year (±$6,950), against $75,081 in South Dakota. In 2015-2019 it was $76,491 in 2024 dollars; the margins of error cannot tell the two periods apart. 6.3% of residents live below the poverty line.
| Measure | Sully County | South Dakota | Change since 2015-2019 |
|---|---|---|---|
| Median household income | $72,578±$6,950 | $75,081 | no clear change |
| Mean household income | $105,002±$13,644 | $98,527 | – |
| Per capita income | $46,134±$5,982 | $40,550 | no clear change |
| People below the poverty line | 6.3%±2.8 pts | 11.9% | no clear change |
| Children under 18 below the poverty line | 0.0%±7.3 pts | 14.3% | – |
| Households receiving SNAP | 4.9%±2.8 pts | 7.9% | – |
| Households with a broadband subscription | 79.6%±6.1 pts | 89.6% | – |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP03) · Check it at data.census.gov
What does housing cost in Sully County?
Owners occupy 72.8% of Sully County's occupied homes and renters 27.2%. The median owner-occupied home is valued at $205,400 by its owner (±$32,262). The median renter pays $842 a month including utilities, and 26.4% of renters pay 35% or more of their income on rent.
| Measure | Sully County | South Dakota | Change since 2015-2019 |
|---|---|---|---|
| Median home value (owner-occupied) | $205,400±$32,262 | $257,400 | no clear change |
| Median gross rent | $842±$206 | $946 | no clear change |
| Renters paying 35% or more of income on rent | 26.4%±13.4 pts | 30.4% | – |
| Median monthly owner costs, with a mortgage | $1,542±$135 | $1,680 | – |
| Owner-occupied homes | 72.8%±6.8 pts | 68.6% | −13.1 pts |
| Housing units | 934±52 | 408,584 | +120 |
| Homeowner vacancy rate | 0.0%±5.2 pts | 0.8% | – |
| Rental vacancy rate | 7.2%±7.0 pts | 6.0% | – |
| Single-family detached homes | 75.6%±4.9 pts | 66.9% | – |
| Mobile homes | 16.0%±4.1 pts | 7.2% | – |
| Built 2020 or later | 0.4%±0.5 pts | 2.3% | – |
| Built 1939 or earlier | 17.1%±4.5 pts | 15.8% | – |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP04) · Check it at data.census.gov
How many new homes is Sully County building?
Builders took permits for 9 new housing units across Sully County in 2025 (9 single-family), 6.1 per 1,000 residents.
Source: Building Permits Survey, annual county files 2019-2025, U.S. Census Bureau · Census Building Permits Survey
How do people in Sully County get to work?
69.2% of Sully County's workers drive alone and 13.4% work from home. The average trip to work takes 19.3 minutes.
| Measure | Sully County | South Dakota | Change since 2015-2019 |
|---|---|---|---|
| In the labor force (age 16+) | 69.3%±4.4 pts | 67.2% | – |
| Unemployment rate | 0.0%±2.8 pts | 2.9% | – |
| Drove alone to work | 69.2%±8.4 pts | 77.0% | – |
| Carpooled | 12.2%±7.9 pts | 8.3% | – |
| Public transportation | 0.0%±2.8 pts | 0.5% | – |
| Walked | 3.2%±1.7 pts | 3.1% | – |
| Worked from home | 13.4%±5.2 pts | 9.7% | no clear change |
| Mean travel time to work | 19.3 min±3.0 | 17.8 min | +6.6 min |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP03) · Check it at data.census.gov
What are Sully County's census tracts?
Sully County is a single census tract.
| Tract 979146119979100 | 1,526±127 | $72,578 |
|---|
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) · Check it at data.census.gov
How does Sully County compare with South Dakota's other counties?
| Measure | Rank |
|---|---|
| Population | 63rd of 66 |
| Growth 2020-2025 | 25th of 66 |
| Residents per square mile | 61st of 66 |
| Median household income | 34th of 66 |
| Median home value | 23rd of 66 |
| Median gross rent | 22nd of 65 |
| Poverty rate | 58th of 65 |
| Bachelor's degree or higher | 39th of 66 |
| Median age | 9th of 66 |
Source: PlainCities ranks from the American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) and PEP Vintage 2025 · How ranks are computed
How these figures are made: methodology and release checks · reading a margin of error · every state · corrections
Not on this page: crime, weather and schools for Sully County are other agencies' records. Crime: the FBI's Crime Data Explorer · climate: NOAA's U.S. Climate Normals · schools: the National Center for Education Statistics' school search.