Township · South Dakota
Big Sioux Township, South Dakota
Big Sioux Township, township, in Union County, South Dakota. Big Sioux Township had 5,152 residents on July 1, 2025 by the Census Bureau's estimate, up 9.8% since 2020; the 2020 Census counted 4,683 and the ACS 2020-2024 5-year estimates put it at 4,917 (±20). GEOID 4612705380.
Residents, July 2025 estimate
5,152
Census Bureau estimate (no margin published)
2020 Census count: 4,683 · ACS 2020-2024: 4,917 ±20
Median household income
$128,005
±$20,937 (90% margin)
South Dakota: $75,081
Median home value
$502,200
±$65,876 (90% margin)
South Dakota: $257,400
Median gross rent
$1,225
±$89 (90% margin)
South Dakota: $946
Where is Big Sioux Township and what county is it in?
Big Sioux Township is a township in Union County, South Dakota. It covers 10.8 square miles of land, 432 residents per square mile in 2020.
One place lies inside Big Sioux Township: Dakota Dunes (CDP, 4,020 in 2020).
Big Sioux Township is in the Sioux City, IA-NE-SD metropolitan statistical area, which takes in 3 counties (Census Bureau delineation, July 2023).
Source: 2024 Gazetteer and 2020 place-by-county files, U.S. Census Bureau · Census reference files
How many people live in Big Sioux Township, and is it growing?
The Census Bureau estimates that 5,152 people lived in Big Sioux Township on July 1, 2025, up 9.8% since 2020, faster than South Dakota (+5.5%). The 2020 Census counted 4,683 residents. The 2020-2024 American Community Survey, a five-year sample, puts the population at 4,917 (±20).
| Measure | Big Sioux Township | Union County | Change since 2015-2019 |
|---|---|---|---|
| Total population | 4,917±20 | 17,081 | +1,233 |
| Households | 1,913±106 | 7,310 | +322 |
| Average household size | 2.57±0.14 | 2.32 | +0.25 |
| Housing units | 1,913±106 | 7,588 | +265 |
Big Sioux Township's population since 2000
From 2,047 in 2000 to 5,152 in 2025: up 151.7%. The 2000, 2010 and 2020 figures are census counts, each for Big Sioux Township as it was drawn that year: a place that annexed land, or a community that has since incorporated, covered a different area then. 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); Census PEP Vintage 2025 (SUB-EST2025, CO-EST2025); 2020 Census P.L. 94-171 · Check it at data.census.gov
Who lives in Big Sioux Township?
The median resident of Big Sioux Township is 41.7 years old; 25.6% are under 18 and 19.7% are 65 or older. The largest group is non-Hispanic white residents at 87.1%, then Hispanic or Latino residents (of any race) at 8.3%.
| Measure | Big Sioux Township | Union County | Change since 2015-2019 |
|---|---|---|---|
| Median age | 41.7±4.0 | 41.5 | no clear change |
| Under 18 years | 25.6%±3.2 pts | 24.1% | – |
| 65 years and over | 19.7%±3.5 pts | 19.5% | – |
| Male | 53.1%±3.1 pts | 51.6% | – |
| Hispanic or Latino (any race) | 8.3%±3.6 pts | 4.8% | no clear change |
| White alone, not Hispanic | 87.1%±4.3 pts | 88.4% | no clear change |
| Black or African American alone, not Hispanic | 0.0%±0.5 pts | 0.9% | – |
| Asian alone, not Hispanic | 0.6%±1.0 pts | 1.1% | – |
| American Indian and Alaska Native alone, not Hispanic | 1.3%±1.4 pts | 0.7% | – |
| Native Hawaiian and Other Pacific Islander alone, not Hispanic | 0.0%±0.5 pts | 0.1% | – |
| Two or more races, not Hispanic | 2.2%±1.5 pts | 3.7% | – |
| Some other race alone, not Hispanic | 0.5%±0.8 pts | 0.2% | – |
| Born outside the United States | 1.4%±1.7 pts | 2.0% | – |
| Speak a language other than English at home (age 5+) | 2.0%±1.9 pts | 3.0% | – |
| Civilian veterans (age 18+) | 6.0%±3.5 pts | 7.6% | – |
| With a disability | 6.6%±3.0 pts | 10.8% | – |
| No health insurance coverage | 1.6%±1.4 pts | 5.1% | – |
| High school graduate or higher (age 25+) | 98.6%±1.3 pts | 95.7% | – |
| Bachelor's degree or higher (age 25+) | 56.3%±7.7 pts | 37.0% | no clear change |
| Graduate or professional degree (age 25+) | 19.6%±8.0 pts | 13.3% | – |
| Lived in the same house a year earlier | 83.4%±7.8 pts | 88.6% | – |
| Moved from another state in the past year | 7.9%±6.5 pts | 4.8% | – |
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 Big Sioux Township earn?
Half of Big Sioux Township's 1,913 households earn less than $128,005 a year (±$20,937), against $89,636 in Union County and $75,081 in South Dakota. In 2015-2019 it was $143,068 in 2024 dollars; the margins of error cannot tell the two periods apart.
| Measure | Big Sioux Township | Union County | Change since 2015-2019 |
|---|---|---|---|
| Median household income | $128,005±$20,937 | $89,636 | no clear change |
| Mean household income | $190,617±$32,882 | $124,814 | – |
| Per capita income | $76,736±$14,511 | $53,834 | no clear change |
| People below the poverty line | 3.2%±2.2 pts | 6.2% | – |
| Children under 18 below the poverty line | 0.0%±2.0 pts | 3.3% | – |
| Households receiving SNAP | 2.0%±2.0 pts | 4.1% | – |
| Households with a computer | 99.4%±1.0 pts | 95.0% | – |
| Households with a broadband subscription | 92.6%±4.7 pts | 89.5% | – |
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 Big Sioux Township?
Owners occupy 73.8% of Big Sioux Township's occupied homes and renters 26.2%. The median owner-occupied home is valued at $502,200 by its owner (±$65,876). The median renter pays $1,225 a month including utilities.
| Measure | Big Sioux Township | Union County | Change since 2015-2019 |
|---|---|---|---|
| Median home value (owner-occupied) | $502,200±$65,876 | $301,100 | +$114,162 |
| Median gross rent | $1,225±$89 | $1,069 | no clear change |
| Renters paying 35% or more of income on rent | 16.9%±12.7 pts | 25.3% | – |
| Median monthly owner costs, with a mortgage | $2,491±$416 | $1,758 | – |
| Owner-occupied homes | 73.8%±6.5 pts | 73.1% | no clear change |
| Renter-occupied homes | 26.2%±6.5 pts | 26.9% | – |
| Housing units | 1,913±106 | 7,588 | +265 |
| Homeowner vacancy rate | 0.0%±1.8 pts | 0.4% | – |
| Rental vacancy rate | 0.0%±4.9 pts | 1.7% | – |
| Single-family detached homes | 72.4%±6.3 pts | 72.0% | – |
| Mobile homes | 1.4%±1.9 pts | 4.2% | – |
| Built 2020 or later | 0.0%±1.3 pts | 1.2% | – |
| Built 2010 to 2019 | 22.9%±7.9 pts | 16.1% | – |
| Built 1939 or earlier | 6.0%±4.8 pts | 16.0% | – |
| Households with no vehicle | 0.0%±1.3 pts | 3.7% | – |
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 do people in Big Sioux Township work and get to work?
83.0% of Big Sioux Township's workers drive alone and 11.2% work from home. The average trip to work takes 12.3 minutes.
| Measure | Big Sioux Township | Union County | Change since 2015-2019 |
|---|---|---|---|
| In the labor force (age 16+) | 66.3%±5.2 pts | 68.4% | – |
| Unemployment rate | 2.7%±4.1 pts | 3.0% | – |
| Drove alone to work | 83.0%±6.7 pts | 82.6% | – |
| Carpooled | 4.8%±3.6 pts | 6.8% | – |
| Public transportation | 0.0%±1.0 pts | 0.0% | – |
| Walked | 1.0%±1.5 pts | 1.3% | – |
| Worked from home | 11.2%±7.2 pts | 7.9% | no clear change |
| Mean travel time to work | 12.3 min±1.8 | 17.7 min | −4.1 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 census tracts are in Big Sioux Township?
1 census tract lies mostly in Big Sioux Township, and 1 more reaches into it (2020 census blocks).
| Tract | Residents, 2020-2024 | Median household income |
|---|---|---|
| Tract 203.01Union County | 4,982 | $117,257 |
| Tract 203.02Union County | 4,813 | $84,013 |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); 2020 block assignment files (tract share = share of the tract's census blocks in Big Sioux Township) · Census block assignment files
How does Big Sioux Township compare with other places in South Dakota?
By the Census Bureau's July 2025 estimates, Big Sioux Township is the 2,247th-most populous of the 16,079 U.S. towns and townships that have one and the most populous of 895 in South Dakota.
Big Sioux Township ranks 8th of 82 places in South Dakota with 1,000 or more residents and a reliable estimate, by median household income.
| Measure | Rank | Of |
|---|---|---|
| Population, July 2025 estimate | 1st | 895 |
| Growth 2020-2025 (PEP) | 12th | 73 |
| Residents per square mile | 67th | 84 |
| Median household income | 8th | 82 |
| Per capita income | 2nd | 83 |
| Median home value | 3rd | 81 |
| Median gross rent | 6th | 72 |
| Bachelor's degree or higher | 2nd | 81 |
| Median age | 29th | 83 |
| Owner-occupied share | 36th | 84 |
| Work from home | 10th | 44 |
| Travel time to work | 66th | 84 |
Big Sioux Township's figures with every place in South Dakota (CSV)
Every place in South Dakota, sortable · Compare Big Sioux Township with other places
Source: PlainCities ranks computed 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 reliable are the figures for Big Sioux Township?
24 of the 57 figures for Big Sioux Township on this page carry a coefficient of variation over 40% and are marked with a ring: they come from a small sample, so read them as rough.
The American Community Survey samples about one household in eight over five years, so every figure is an estimate with a 90% margin of error (shown under each value). A ring marks an estimate whose coefficient of variation is over 40%. A change is called only when the gap between the two periods is larger than their combined 90% margin (the square root of the sum of the two squared margins), the Census Bureau's test. How to read a margin of error.
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026): margins of error as published · ACS technical documentation
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 Big Sioux Township 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.