1,535,909 people (2024 Census estimate, +0.9% since 2020)
911 square miles of land · 1,686 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.
26 active community water systems list Suffolk County in the area they serve, reporting 1,368,598 people served in all (a system that crosses county lines counts its whole population).
| SUFFOLK COUNTY WATER AUTHORITY groundwater · local government · NY5110526 | 1,100,000 served |
| SOUTH HUNTINGTON WATER DISTRICT groundwater · local government · NY5103263 | 81,760 served |
| GREENLAWN WATER DISTRICT groundwater · local government · NY5103271 | 42,000 served |
| RIVERHEAD WATER DISTRICT groundwater · local government · NY5103705 | 35,000 served |
| DIX HILLS WATER DISTRICT groundwater · local government · NY5103276 | 34,522 served |
| SMITHTOWN WATER DISTRICT buys groundwater · local government · NY5105656 | 19,635 served |
| HAMPTON BAYS WATER DISTRICT groundwater · local government · NY5103704 | 12,500 served |
| ROBERT MOSES STATE PARK groundwater · state · NY5117671 | 11,600 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 1,092 people were held in Suffolk County's jail, in Vera's latest figure (2026). In 2021 it was about 759.
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.
68 school districts have their office in Suffolk County. School taxes are usually the largest part of a property tax bill.
Spent $519.8 million — $490.9 million to run schools, about $26,790 per student, plus $7.2 million on buildings and equipment. Money in: $120.7 million local (mostly property tax), $393.3 million state, $44 million federal. Long-term debt: $99.1 million.
Spent $385.1 million — $349.1 million to run schools, about $29,473 per student, plus $11.7 million on buildings and equipment. Money in: $201.8 million local (mostly property tax), $155 million state, $19.9 million federal. Long-term debt: $92.8 million.
Spent $275.9 million — $261.6 million to run schools, about $27,519 per student, plus $4.6 million on buildings and equipment. Money in: $147.6 million local (mostly property tax), $119.2 million state, $15.4 million federal. Long-term debt: $111.9 million.
Spent $290 million — $271.3 million to run schools, about $29,595 per student, plus $12.2 million on buildings and equipment. Money in: $92.2 million local (mostly property tax), $181.2 million state, $23 million federal. Long-term debt: $2.3 million.
Spent $280.1 million — $265.5 million to run schools, about $29,917 per student, plus $7.8 million on buildings and equipment. Money in: $150.4 million local (mostly property tax), $123 million state, $22.5 million federal. Long-term debt: $42.3 million.
Spent $283.7 million — $265.6 million to run schools, about $33,520 per student, plus $10 million on buildings and equipment. Money in: $207.9 million local (mostly property tax), $64.9 million state, $11.3 million federal. Long-term debt: $14 million.
Spent $255 million — $235.9 million to run schools, about $29,855 per student, plus $16.9 million on buildings and equipment. Money in: $98.2 million local (mostly property tax), $166 million state, $26.2 million federal. Long-term debt: $26.8 million.
Spent $223.5 million — $197.4 million to run schools, about $26,494 per student, plus $2.4 million on buildings and equipment. Money in: $119.2 million local (mostly property tax), $95.1 million state, $14.6 million federal. Long-term debt: $48.4 million.
And 60 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 Suffolk County about $320.5 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.
369 bridges in Suffolk County: 98 in good condition, 264 fair, and 7 poor (1.9%). “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 27 over NORTH RD · built 1959 | 39,182 vehicles a day |
| NICOLLS ROAD NB over PORTION ROAD PORTION RO · built 1970 | 36,843 vehicles a day |
| LINCOLN AVE over 27 27 07051193 RTE 27 · built 1996 | 10,648 vehicles a day |
| FLOYD PKWY EXT over NARROW BAY · built 1959 | 4,381 vehicles a day |
| CRANBERRY HOLE RD over LONG ISLAND-MK BR · built 1895 | 1,327 vehicles a day |
| RIVER AVENUE over LONG ISLAND-MK BR · built 1907 | 337 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $492.1 million of work in Suffolk County in fiscal 2025, about $322 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 Suffolk 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 Suffolk County built: brayden.ozark@gmail.com.
More of New York: the state government and every county in New York.
Nearby counties: South Central Connecticut Planning Region, CT (25 mi) · Greater Bridgeport Planning Region, CT (32 mi) · Lower Connecticut River Valley Planning Region, CT (34 mi) · Naugatuck Valley Planning Region, CT (45 mi) · Western Connecticut Planning Region, CT (46 mi) · Southeastern Connecticut Planning Region, CT (48 mi).