23,509 people (2024 Census estimate, +1.0% since 2020)
521 square miles of land · 45 people per square mile
“Highest” and “lowest” are just order, not grades: a high rank for poverty or hazard losses means more of it. Each figure's source is in its section below.
10 active community water systems list Yankton County in the area they serve, reporting 30,351 people served in all (a system that crosses county lines counts its whole population).
| YANKTON groundwater · local government · SD4600423 | 15,411 served |
| BY WATER DISTRICT surface water · local government · SD4600865 | 13,320 served |
| IRENE buys surface water · local government · SD4600173 | 422 served |
| GAYVILLE buys groundwater · local government · SD4600140 | 392 served |
| MISSION HILL buys surface water · local government · SD4600212 | 190 served |
| EAST WINDS COURT, INC. buys surface water · private · SD4602099 | 180 served |
| VOLIN buys surface water · local government · SD4600347 | 161 served |
| LESTERVILLE buys surface water · local government · SD4600195 | 115 served |
Source: U.S. EPA Safe Drinking Water Information System (SDWIS), active community systems, . Look up any system's violations and test results with EPA's search using its ID.
No county jail figure in the national data for Yankton County — not gathered, never hidden. Some counties share a regional jail or have none.
2 school districts have their office in Yankton County. School taxes are usually the largest part of a property tax bill.
Spent $37.2 million — $33.5 million to run schools, about $11,022 per student, plus $3.7 million on buildings and equipment. Money in: $20.3 million local (mostly property tax), $13.8 million state, $4.5 million federal.
Spent $4 million — $3.4 million to run schools, about $11,882 per student, plus $408,000 on buildings and equipment. Money in: $1.5 million local (mostly property tax), $2.1 million state, $469,000 federal. Long-term debt: $2.3 million.
Source: U.S. Census Bureau, 2023 Annual Survey of School System Finances. Districts are listed by the county of their main office; some serve neighboring counties too.
Source: County Health Rankings & Roadmaps 2025 (University of Wisconsin Population Health Institute), which gathers federal data (CDC, Census, and others); measures cover different recent years. Blank lines aren't reported for small counties.
Overall risk: Relatively Low compared with other U.S. counties. FEMA estimates natural hazards cost Yankton County about $19.4 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Very High; social vulnerability: Relatively High.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
99 bridges in Yankton County: 42 in good condition, 44 fair, and 13 poor (13.1%). “Poor” means a main part — the deck, the beams, or the supports — is rated 4 or lower on the federal 0–9 scale. It doesn't mean unsafe to drive; unsafe bridges are closed.
| W 23RD STREET over MARNE CREEK · built 1976 | 3,980 vehicles a day |
| CEDAR STREET over MARNE CREEK · built 1978 | 969 vehicles a day |
| 29280 431ST AVENUE over JAMES RIVER · built 1959 | 315 vehicles a day |
| 30430 446TH AVENUE over UNNAMED CREEK · built 1941 | 100 vehicles a day |
| 44930 295 ST over TURKEY CREEK · built 1991 | 75 vehicles a day |
| 44960 296 ST over TURKEY CREEK · built 1979 | 75 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $14.1 million of work in Yankton County in fiscal 2025, about $604 per resident — to the county, cities, schools, hospitals, nonprofits and others.
Source: USAspending.gov, grants by place of performance, fiscal 2025 (Oct. 2024 to Sept. 2025). Search it by county to see each award.
From Grants.gov: posted grants listing county governments as eligible, soonest deadline first; research-only and overseas programs left out; list updated 2026-10-13, refreshed weekly. 62 are open in all. Cities, towns, school districts and nonprofits have their own lists there.
Registration deadlines, early voting and polling places for South Dakota are on the federal site vote.gov, which links to the state's official election office.
The budget, property tax rates, audits, local officials and offices for Yankton County come from the county's own records, which we haven't gathered — not gathered, never hidden. See what a full county site looks like, or ask to have Yankton County built: brayden.ozark@gmail.com.
More of South Dakota: the state government and every county in South Dakota.
Nearby counties: Clay County (22 mi) · Turner County (24 mi) · Bon Homme County (25 mi) · Cedar County, NE (29 mi) · Hutchinson County (29 mi) · Knox County, NE (36 mi).