New Hampshire bridge conditions
2,549 inventoried bridges · 192 rated poor · county by county
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- 192 of New Hampshire's 2,549 inventoried bridges are rated in poor condition (7.5%) in the 2025 National Bridge Inventory, as of .
- 1,303 bridges (51.1%) are rated good and 1,054 (41.3%) fair.
- The national poor rate is about 6.7%; New Hampshire is above it (see all states ranked).
- The busiest poor-rated bridge in the state is I-89 over South Street in Merrimack County, carrying about 46,612 vehicles a day.
By the measure that matters most - the most traffic on a poor rating - it is I-89 over South Street in Merrimack County, built 1959, carrying about 46,612 vehicles a day. That is a repair-priority flag, not a collapse warning: what a poor rating does and does not mean. See the worst bridge in every state.
Good 51.1% · Fair 41.3% · Poor 7.5% of 2,549 bridges
Bridge conditions by county
Sorted by the number of poor-rated bridges. Click any county for its full bridge list.
| County | Bridges | Rated poor | Poor % |
|---|---|---|---|
| Grafton County | 547 | 43 | 7.9% |
| Hillsborough County | 385 | 31 | 8.1% |
| Merrimack County | 326 | 27 | 8.3% |
| Rockingham County | 309 | 22 | 7.1% |
| Cheshire County | 194 | 22 | 11.3% |
| Strafford County | 136 | 13 | 9.6% |
| Carroll County | 193 | 10 | 5.2% |
| Coos County | 189 | 10 | 5.3% |
| Sullivan County | 158 | 9 | 5.7% |
| Belknap County | 112 | 5 | 4.5% |
The 25 busiest poor-rated bridges in New Hampshire
Frequently asked questions
How many bridges in New Hampshire are in poor condition?
192 of New Hampshire's 2,549 inventoried highway bridges are rated in poor condition (7.5%) in the 2025 National Bridge Inventory. 'Poor' is FHWA's classification for a bridge whose deck, superstructure, or substructure is rated 4 or lower on the 0-9 scale; it was formerly called 'structurally deficient'.
Are the poor-rated bridges in New Hampshire safe to drive on?
A poor rating flags advanced deterioration that needs repair or close monitoring; it does not by itself mean a bridge is unsafe. Bridges judged unsafe are closed or restricted to lighter loads by the owner. Inspections continue on all open bridges, generally at least every 24 months under the National Bridge Inspection Standards.
Source: FHWA National Bridge Inventory, 2025 vintage, reported by the New Hampshire DOT.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.