256,400 people (2024 Census estimate, −1.9% since 2020)
520 square miles of land · 493 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.
14 active community water systems list Marin County in the area they serve, reporting 257,757 people served in all (a system that crosses county lines counts its whole population).
| MARIN MUNICIPAL WATER DISTRICT surface water · local government · CA2110002 | 188,116 served |
| NORTH MARIN WATER DISTRICT surface water · local government · CA2110003 | 61,691 served |
| BOLINAS COMMUNITY PUD surface water · local government · CA2110005 | 1,937 served |
| NORTH MARIN WD - PT. REYES groundwater · local government · CA2110006 | 1,841 served |
| INVERNESS PUBLIC UTILITY DIST surface water · local government · CA2110001 | 1,445 served |
| LAWSON S LANDING groundwater · private · CA2110008 | 946 served |
| STINSON BEACH COUNTY WTR DIST surface water · local government · CA2110004 | 583 served |
| COAST SPRINGS - CAL. WATER SERVICE (PUC) surface water · private · CA2110007 | 445 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 261 people were held in Marin County's jail, in Vera's latest figure (2025). In 2020 it was about 194.
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.
18 school districts have their office in Marin County. School taxes are usually the largest part of a property tax bill.
Spent $157.9 million — $115.1 million to run schools, about $15,969 per student, plus $31.8 million on buildings and equipment. Money in: $80.7 million local (mostly property tax), $63.7 million state, $9.1 million federal. Long-term debt: $228.1 million.
Spent $116.4 million — $108 million to run schools, about $22,335 per student, plus $3.6 million on buildings and equipment. Money in: $117.7 million local (mostly property tax), $15.9 million state, $2.1 million federal. Long-term debt: $86.8 million.
Spent $103.4 million — $86.4 million to run schools, about $20,143 per student, plus $7.7 million on buildings and equipment. Money in: $56.6 million local (mostly property tax), $56.1 million state, $8.2 million federal. Long-term debt: $124.2 million.
Spent $81.3 million — $50.5 million to run schools, about $18,946 per student, plus $19.7 million on buildings and equipment. Money in: $51.3 million local (mostly property tax), $19.8 million state, $3.7 million federal. Long-term debt: $165.4 million.
Spent $54.8 million — $50.2 million to run schools, about $21,199 per student, plus $1.9 million on buildings and equipment. Money in: $48.7 million local (mostly property tax), $7.9 million state, $1.5 million federal. Long-term debt: $65.7 million.
Spent $35.5 million — $32.1 million to run schools, about $17,596 per student, plus $535,000 on buildings and equipment. Money in: $22.2 million local (mostly property tax), $19.7 million state, $1.5 million federal. Long-term debt: $30.8 million.
Spent $31.6 million — $28.3 million to run schools, about $16,401 per student, plus $149,000 on buildings and equipment. Money in: $25.3 million local (mostly property tax), $8.9 million state, $1.2 million federal. Long-term debt: $57.2 million.
Spent $22.6 million — $22.1 million to run schools, about $17,502 per student, plus $287,000 on buildings and equipment. Money in: $18.3 million local (mostly property tax), $6.3 million state, $583,000 federal. Long-term debt: $51.8 million.
And 10 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 Marin County about $259.3 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.
207 bridges in Marin County: 91 in good condition, 100 fair, and 16 poor (7.7%). “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.
| U.S. HIGHWAY 101 over NOVATO CREEK · built 1974 | 61,500 vehicles a day |
| SIR FRANCIS DRAKE over LAGUNITAS CREEK · built 1964 | 25,582 vehicles a day |
| U.S. HIGHWAY 101 over CORTE MADERA CR & EB SFD · built 1959 | 19,700 vehicles a day |
| FREITAS PKWY over U.S. HIGHWAY 101 · built 1960 | 18,000 vehicles a day |
| IGNACIO BOULEVARD over U.S. HIGHWAY 101 · built 1964 | 12,900 vehicles a day |
| LINCOLN AVE over SAN RAFAEL CREEK · built 1959 | 11,601 vehicles a day |
Source: Federal Highway Administration, National Bridge Inventory (2025 submission). Includes state, county and city bridges.
Federal grants paid for $546.3 million of work in Marin County in fiscal 2025, about $2,082 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.
General election: Tuesday, November 3, 2026. Ballots mailed; drop boxes open: 2026-10-05. Last day to register to vote: 2026-10-19. Early in-person voting: 2026-10-24 to 2026-11-03. Election Day: 2026-11-03. Last day for mailed ballots to arrive: 2026-11-10.
Source: California Secretary of State — Nov. 3, 2026 key dates · California Official Voter Information Guide — dates to remember · California Secretary of State — make a plan to vote
The budget, property tax rates, audits, local officials and offices for Marin 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 Marin County built: brayden.ozark@gmail.com.
More of California: the state government and every county in California.
Nearby counties: San Francisco County (27 mi) · Sonoma County (34 mi) · Napa County (39 mi) · Contra Costa County (44 mi) · Solano County (46 mi) · San Mateo County (48 mi).