In 2025, fire departments serving Mercer County responded to 2,830 fire and hazmat incidents — including a single $500K property loss. FEMA NRI rates wildfire risk here as High.
Gas leak (natural gas or LPG) lead by count. Top five categories make up about 54% of all calls.
Jun peaks. Dec dips.
11,991 incidents from 2021 through 2025.
| Year | Incidents | |
|---|---|---|
| 2021 | 1,496 | |
| 2022 | 3,090 | |
| 2023 | 1,979 | |
| 2024 | 2,596 | |
| 2025 | 2,830 |
For the 247 building fires departments responded to in 2025, here's how investigators classified them.
Largest single-incident property losses in Mercer County during 2025. These 10 fires alone account for 69% of the county's total.
| # | Property loss | City | Type | Severity |
|---|---|---|---|---|
| 1 | $500,000 | Ewing | Building fires | Major |
| 2 | $300,000 | Hamilton | Building fires | Major |
| 3 | $300,000 | Lawrence | Building fires | Major |
| 4 | $300,000 | Ewing | Building fires | Major |
| 5 | $270,000 | Hamilton | Building fires | Major |
| 6 | $250,000 | Hamilton | Building fires | Major |
| 7 | $226,800 | East Windsor | Building fires | Significant |
| 8 | $100,000 | Hamilton | Building fires | Significant |
| 9 | $100,000 | Hamilton | Building fires | Significant |
| 10 | $100,000 | Robbinsville | Road freight or transport vehicle fire | Significant |
Per-capita rates let us compare apples to apples.
12 cities mapped to FIPS 34021.
| City | Population | |
|---|---|---|
| Hamilton | 91,819 | View › |
| Trenton | 90,055 | View › |
| Ewing | 36,140 | View › |
| Lawrence | 32,636 | View › |
| Princeton | 30,450 | View › |
| East Windsor | 29,784 | View › |
| West Windsor | 29,445 | View › |
| Robbinsville | 15,413 | View › |
| Mercerville | 14,364 | View › |
| Hamilton Square | 11,894 | View › |
| White Horse | 9,692 | View › |
| Twin Rivers | 8,144 | View › |
20 departments report from this county.
Top 6 fire perimeters by acres burned (state-scoped fallback while we build out per-county polygons).
| # | Name | Year | Agency | Acres |
|---|---|---|---|---|
| 1 | NJGSR-FY19-RX-Pool 3b | 2019 | FWS | 83 |
| 2 | NJWKR-FY19-RX-Kenely Unit D | 2019 | FWS | 4 |
| 3 | Game Farm | 2024 | FWS | 1 |
| 4 | NJGSR-FY20-WF-Orange Trail WF | 2020 | FWS | 0 |
| 5 | NJWKR-FY20-WF-Papakating Creek WF | 2020 | FWS | 0 |
| 6 | Water Works | 2023 | FWS | 0 |
County-level NFIRS aggregates for 2025, plus 5-year totals across 2021–2025. NFIRS is voluntary — about 23,000 of roughly 30,000 US fire departments report — so totals are a strong indicator, not a complete census. Wildfire risk score (0–100) and Expected Annual Loss come from FEMA's National Risk Index. Drought class is the most recent USDM classification (D0 = abnormally dry through D4 = exceptional drought). Historical fire perimeters are sourced from the NIFC InterAgency Fire Perimeter History.