1,392,438 people (2024 Census estimate, +0.1% since 2020)
285 square miles of land · 4,894 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.
40 active community water systems list Nassau County in the area they serve, reporting 1,354,175 people served in all (a system that crosses county lines counts its whole population).
| LIBERTY UTILITIES NEW YORK - LYNBROOK groundwater · private · NY2902835 | 220,000 served |
| LIBERTY UTILITIES NEW YORK - MERRICK groundwater · private · NY2902840 | 135,000 served |
| WA OF WESTERN NASSAU groundwater · public/private · NY2902830 | 120,000 served |
| TOWN OF HEMPSTEAD WATER DEPARTMENT groundwater · local government · NY2900000 | 110,000 served |
| JERICHO WD groundwater · public/private · NY2902831 | 58,000 served |
| HEMPSTEAD (V) groundwater · local government · NY2902827 | 56,000 served |
| HICKSVILLE WD groundwater · local government · NY2902829 | 48,000 served |
| FREEPORT (V) groundwater · local government · NY2902823 | 45,000 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 691 people were held in Nassau County's jail, in Vera's latest figure (2026). In 2021 it was about 747.
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.
56 school districts have their office in Nassau County. School taxes are usually the largest part of a property tax bill.
Spent $232.3 million — $218.2 million to run schools, about $27,747 per student, plus $7.1 million on buildings and equipment. Money in: $154.2 million local (mostly property tax), $72.9 million state, $9.9 million federal. Long-term debt: $67.3 million.
Spent $254.3 million — $229 million to run schools, about $29,347 per student, plus $14.8 million on buildings and equipment. Money in: $143.2 million local (mostly property tax), $73 million state, $19.9 million federal. Long-term debt: $47.3 million.
Spent $225.5 million — $218.2 million to run schools, about $30,404 per student, plus $5.9 million on buildings and equipment. Money in: $147.1 million local (mostly property tax), $86.5 million state, $6.6 million federal. Long-term debt: $4.4 million.
Spent $268 million — $247.8 million to run schools, about $35,718 per student, plus $9.8 million on buildings and equipment. Money in: $224.5 million local (mostly property tax), $34.4 million state, $5 million federal. Long-term debt: $84.7 million.
Spent $270.4 million — $246.2 million to run schools, about $36,016 per student, plus $17 million on buildings and equipment. Money in: $240.9 million local (mostly property tax), $17.4 million state, $5.4 million federal. Long-term debt: $57.2 million.
Spent $222.1 million — $208.3 million to run schools, about $31,865 per student, plus $2.9 million on buildings and equipment. Money in: $169.9 million local (mostly property tax), $52.3 million state, $5.8 million federal. Long-term debt: $66.1 million.
Spent $205.3 million — $200.4 million to run schools, about $30,972 per student, plus $3.2 million on buildings and equipment. Money in: $88.6 million local (mostly property tax), $120.3 million state, $22.3 million federal. Long-term debt: $7.6 million.
Spent $278.3 million — $244 million to run schools, about $39,286 per student, plus $24.7 million on buildings and equipment. Money in: $144 million local (mostly property tax), $94.4 million state, $23.2 million federal. Long-term debt: $71.2 million.
And 48 more.
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 Nassau County about $298.6 million a year on average in buildings, crops and lives. Ability to bounce back (community resilience): Very High; social vulnerability: Relatively Low.
Source: FEMA National Risk Index (December 2025), expected annual loss. Ratings compare counties nationwide; they're estimates, not predictions.
328 bridges in Nassau County: 91 in good condition, 234 fair, and 3 poor (0.9%). “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.
| RTE 908G over RTE I495 · built 1968 | 129,086 vehicles a day |
| BRIDGE ROAD over LONG ISLAND-PT WS · built 1898 | 1,088 vehicles a day |
| SEAWANE DRIVE over AUERBACH CHANNEL · built 1932 | 0 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $200 million of work in Nassau County in fiscal 2025, about $143 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 New York 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 Nassau 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 Nassau County built: brayden.ozark@gmail.com.
More of New York: the state government and every county in New York.
Nearby counties: Queens County (14 mi) · Bronx County (16 mi) · Kings County (20 mi) · New York County (20 mi) · Hudson County, NJ (26 mi) · Bergen County, NJ (30 mi).