County outline
Where Yankton County is located
Area breakdown
Land accounts for 97.9% of Yankton County’s measured area and water for 2.1%. Its combined area converts to 1,378.5 square kilometers or approximately 340,647 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 521.189 | 1,349.873 | 333,561 |
| Water | 11.072 | 28.676 | 7,086.1 |
| Total | 532.261 | 1,378.55 | 340,647 |
How Yankton County compares
By original Census land area, Yankton County ranks #58 of 66 in South Dakota and #2003 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.573 times the South Dakota county-equivalent median of 909.3 square miles. It accounts for 0.7% of the combined county land area in the state.
See the complete South Dakota ranking · What counts as a county equivalent?
Population and density of Yankton County
The Census Bureau estimates that 23,635 people lived in Yankton County on July 1, 2025. That ranks #1,716 of 3,222 county equivalents nationally and #9 of 66 in South Dakota. Since the April 1, 2020 estimates base of 23,317, the population has grown by 318 (+1.4%), compared with +5.5% for South Dakota as a whole.
With 521.2 square miles of land, that is 45 people per square mile (18 per km²), placing Yankton County #1,645 nationally for density and #5 in South Dakota. The median county equivalent has 47 people per square mile; the South Dakota median is 5.7. Put another way, there are about 14 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 23,291 | 23,359 | 23,418 | 23,505 | 23,577 | 23,635 |
| Change | — | +68 | +59 | +87 | +72 | +58 |
U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.
Cities and towns in Yankton County
7 incorporated places lie at least partly in Yankton County. Together they are home to 16,719 people (70.7%); the other 6,916 (29.3%) live outside any incorporated place, in unincorporated communities and rural areas.
The largest is Yankton city, with 15,816 residents in the county.
| Incorporated place | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Yankton cityCounty seat | 15,816 | +2.4% | 8.739 |
| Gayville town | 375 | −3.6% | 0.242 |
| Mission Hill town | 187 | −3.6% | 0.328 |
| Volin town | 157 | −0.6% | 0.197 |
| Lesterville town | 110 | 0% | 0.202 |
| Utica town | 69 | −2.8% | 0.264 |
| Irene cityAlso in 2 other counties | 5 | 0% | 0.285 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Yankton County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.
Metropolitan area
Yankton County is a central county of the Yankton, SD Micropolitan Statistical Area. Yankton County is the area’s only county equivalent, so the micro area has the same 521.2 square miles of land. By combined land it ranks #421 of 542 micropolitan areas, and #488 by population.
ZIP codes
10 ZIP Code Tabulation Areas have land in Yankton County; 7 of them have most of their land inside the county, and the others mainly cover neighboring areas.
57031570375704057045570465706357067570705707257078
ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area.
Counties bordering Yankton County
Yankton County shares a land border with 6 county equivalents, including 2 in Nebraska. It has more land than 1 of them. The largest neighbor is Knox County (1,108.2 mi²) and the smallest is Clay County (412 mi²). Together with its neighbors, Yankton County forms a block of 4,775.3 mi² of land, of which it holds 10.9%.
| Bordering county equivalent | Land mi² | Size vs. Yankton | Compare |
|---|---|---|---|
| Knox CountyNebraska | 1,108.2 | 2.1× larger | Compare |
| Hutchinson County | 813 | 1.6× larger | Compare |
| Cedar CountyNebraska | 740.2 | 1.4× larger | Compare |
| Turner County | 617.1 | 1.2× larger | Compare |
| Bon Homme County | 563.5 | 1.1× larger | Compare |
| Clay County | 412 | 1.3× smaller | Compare |
How big is Yankton County compared with U.S. states?
Yankton County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 2 times as much. South Dakota’s county land could hold about 145 areas the size of Yankton County.
Another way to picture it: the same land area would fill a square about 22.8 miles (36.7 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.
State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.
What stands out about Yankton County?
Yankton County has more land than 1,219 of the other 3,221 county equivalents in the dataset.
A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.
Does including water change its rank?
Using land plus water places Yankton County at #2,070 nationally by total area, 67 places farther from the top than its land rank. Other county equivalents gain more area when their water measurements are included.
Its water share is 2.1%, compared with a national county-equivalent median of 1.2% — 0.9 percentage points higher. This describes the statistical geography’s land/water mix, not flood exposure or developable land.
Closest positions in the national land ranking
These entries sit immediately beside Yankton County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #2002 | Kanabec County, Minnesota | 521.6 | Compare |
| #2003 | Yankton County, South Dakota | 521.2 | This county |
| #2004 | Marin County, California | 520.1 | Compare |
Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.
Representative coordinates
The Census internal point is 43.006603, -97.388361. It represents a location inside the geography; it is not necessarily the centroid or the address of a courthouse.
Source and precision
U.S. Census Bureau, 2026 Gazetteer Files, Counties. Original ALAND: 1,349,873,602 m²; AWATER: 28,676,585 m². Rankings use ALAND; exact ties use ascending GEOID. Tables preserve Census-published square miles to three decimals, with conversions based on those values.
Common questions
How big is Yankton County?
Yankton County, South Dakota has 521.2 square miles (1,349.9 km²) of land and 11.1 square miles of water, for a total area of 532.3 square miles. It ranks #2003 of 3,222 U.S. county equivalents by land area.
Is Yankton County the largest county in South Dakota?
No. Yankton County ranks #58 of 66 in South Dakota by land area. The largest is Meade County, with 3,470.9 square miles of land.
What counties border Yankton County?
Yankton County shares a land border with Bon Homme County, Clay County, Cedar County, Nebraska, Turner County, Hutchinson County, and Knox County, Nebraska.
What is the population of Yankton County?
The Census Bureau estimates Yankton County had 23,635 residents on July 1, 2025, ranking #1,716 of 3,222 county equivalents. That is 45 people per square mile of land.
What is the county seat of Yankton County?
The county seat of Yankton County is Yankton.
What cities and towns are in Yankton County?
Yankton County has 7 incorporated places. The most populous five are Yankton city, Gayville town, Mission Hill town, Volin town, and Lesterville town; 6,916 residents live outside any incorporated place.
Is Yankton County part of a metropolitan area?
Yes. It is a central county of the Yankton, SD Micropolitan Statistical Area.
How many ZIP codes are in Yankton County?
10 ZIP Code Tabulation Areas have land in Yankton County, and 7 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Yankton County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 2 times as much land.
How many acres of land are in Yankton County?
The land measurement converts to approximately 333,561 acres. Including water, total area is approximately 340,647 acres. One square mile equals 640 acres.
Why might another source show a different area?
Check whether it reports land or total area, its Census vintage, and its rounding. Our guide explains how to reconcile county area figures.
Can this establish a property boundary?
No. Statistical measurements and generalized maps do not establish property lines. Consult the relevant local surveying or land-records authority.