632,276 people (2024 Census estimate, +3.5% since 2020)
474 square miles of land · 1,335 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.
7 active community water systems list Johnson County in the area they serve, reporting 670,249 people served in all (a system that crosses county lines counts its whole population).
| WATER DISTRICT 1 OF JOHNSON CO surface water · local government · KS2009110 | 490,000 served |
| OLATHE, CITY OF surface water · local government · KS2009115 | 143,014 served |
| GARDNER, CITY OF surface water · local government · KS2009106 | 23,942 served |
| JOHNSON CO RWD 7 buys surface water · local government · KS2009104 | 6,457 served |
| DESOTO, CITY OF groundwater · local government · KS2009102 | 4,645 served |
| EDGERTON, CITY OF buys surface water · local government · KS2009103 | 1,741 served |
| CLEARVIEW CITY, CITY OF buys groundwater · local government · KS2009123 | 450 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.
About 747 people were held in Johnson County's jail, in Vera's latest figure (2024), or 186 per 100,000 residents ages 15–64. In 2019 it was about 827.
Source: Vera Institute of Justice, Incarceration Trends (built from federal Bureau of Justice Statistics jail surveys). Counties without their own jail, or that share one, may show no figure.
6 school districts have their office in Johnson County. School taxes are usually the largest part of a property tax bill.
Spent $447.8 million — $415.8 million to run schools, about $14,323 per student, plus $7.9 million on buildings and equipment. Money in: $196.7 million local (mostly property tax), $304.2 million state, $26.6 million federal. Long-term debt: $765.8 million.
Spent $442.2 million — $326.9 million to run schools, about $12,283 per student, plus $102.5 million on buildings and equipment. Money in: $161.3 million local (mostly property tax), $220.8 million state, $29.3 million federal. Long-term debt: $404.7 million.
Spent $335.1 million — $280.9 million to run schools, about $12,547 per student, plus $42.1 million on buildings and equipment. Money in: $194.3 million local (mostly property tax), $177.7 million state, $23.2 million federal. Long-term debt: $376.2 million.
Spent $108.2 million — $91.2 million to run schools, about $12,253 per student, plus $11.7 million on buildings and equipment. Money in: $42.4 million local (mostly property tax), $68.6 million state, $5.8 million federal. Long-term debt: $160.6 million.
Spent $85.3 million — $77.6 million to run schools, about $12,953 per student, plus $3.3 million on buildings and equipment. Money in: $27.3 million local (mostly property tax), $66.3 million state, $7.6 million federal. Long-term debt: $114.2 million.
Spent $83.2 million — $58.7 million to run schools, about $10,928 per student, plus $16.4 million on buildings and equipment. Money in: $23.3 million local (mostly property tax), $53.2 million state, $2.8 million federal. Long-term debt: $220.9 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 High compared with other U.S. counties. FEMA estimates natural hazards cost Johnson County about $256.8 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Relatively High; social vulnerability: Very Low.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
785 bridges in Johnson County: 593 in good condition, 180 fair, and 12 poor (1.5%). “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.
| COLLEGE BLVD over INDIAN CK · built 1976 | 24,000 vehicles a day |
| K10 HWY WB over KILL CREEK · built 1975 | 16,300 vehicles a day |
| 103RD. STREET over TRIB. TO INDIAN CREEK · built 1975 | 8,342 vehicles a day |
| KENNETH RD over NEGRO CK · built 1910 | 7,700 vehicles a day |
| 83RD ST. E.47-16.5 over RAILROAD · built 1948 | 1,835 vehicles a day |
| GREENWOOD ST. #49 over INDIAN CREEK TRIB. · built 1989 | 1,730 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $225.2 million of work in Johnson County in fiscal 2025, about $369 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 Kansas 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 Johnson 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 Johnson County built: brayden.ozark@gmail.com.
More of Kansas: the state government and every county in Kansas.
Nearby counties: Wyandotte County (16 mi) · Miami County (22 mi) · Leavenworth County (24 mi) · Douglas County (25 mi) · Jackson County, MO (27 mi) · Cass County, MO (30 mi).