Opening Snapshot
New Hampshire has 2,549 bridges. (ARTBA 2025) Of those, 192 are rated in poor condition, a rate of 8% against a national average of 6.7%. The state ranks #14 nationally, and roughly 886,901 vehicles cross its poor-condition bridges every day. (ARTBA 2025)
New Hampshire is the only state in the top 15 for poor-bridge rate with neither an income tax nor a sales tax. That distinction is not incidental. It defines the revenue ceiling for every transportation program in the state and sets the boundary conditions for bridge repair. The gas tax and turnpike tolls are the primary funding tools, and both have structural limits.
NHDOT tracks 324 bridges on its Red List, which is considerably more than the 192 reported by ARTBA. The difference is scope: the Red List includes structures shorter than 20 feet, which fall below the federal National Bridge Inventory reporting threshold, and applies NHDOT's own criteria rather than federal NBI ratings. The ARTBA count covers only federally reportable bridges. (NHDOT; ARTBA 2025)
New Hampshire also has 54 covered bridges, including the Cornish-Windsor Bridge, the longest wooden covered bridge in the United States, which anchors a tourism economy that depends on the state's rural road network. (NHDOT)
The Red List
NHDOT's Red List is the closest thing to a public bridge accountability system in any state covered in this series. The program tracks bridges that meet state-defined criteria for structural concern, publishes the full list annually with maps, and requires twice-annual inspections for state-owned Red List bridges and annual inspections for municipal ones. Both cadences are faster than the standard federal biennial cycle. (NHDOT)
As of the end of the 2024 inspection cycle, 324 bridges sit on the Red List: 112 state-owned and 212 municipal. The state list has dropped from 133 a decade ago, while the municipal list has trended down since 2017, when SB 38 narrowed the definitional criteria. Direction is positive. Pace is slow. (NHDOT)
No other state in this series maintains a comparable public tracking mechanism. The Red List publishes bridge-level data with maps, enforces accelerated inspection schedules, and has operated continuously for over a decade. It does not fix bridges. It ensures that the state, municipalities, and the public know exactly which ones need fixing and how quickly they are deteriorating. That transparency is the distinguishing feature of New Hampshire's approach.
President Biden visited a Red List bridge in 2021 (Route 175 over the Pemigewasset River in Woodstock) to promote the Infrastructure Investment and Jobs Act. (White House)
The full state profile is available on ARTBA's New Hampshire bridge report.
Who Owns What
New Hampshire has no county highway departments. Towns and cities maintain their own bridges directly, without a county intermediary. This structural feature makes the municipal ownership burden more acute than in states where counties can pool resources across jurisdictions.
Municipal bridges carry a 9.6% poor rate, nearly double the state highway agency's 5.8%. Municipalities own 39% of the total bridge inventory but account for 49% of all poor bridges. (FHWA NBI 2024)
| Owner | Bridges | Poor | % Poor |
|---|---|---|---|
| State Highway Agency | 1,303 | 76 | 5.8% |
| City/Municipal | 982 | 94 | 9.6% |
| State Toll Authority | 167 | 9 | 5.4% |
| Federal/Tribal | 80 | 10 | 12.5% |
| Other | 10 | 2 | 20.0% |
| Total | 2,542 | 191 |
This table uses FHWA 2024 NBI data, which totals 2,542 bridges and 191 poor. The ARTBA 2025 headline figures (2,549 total, 192 poor) draw from a slightly different data vintage. Both are valid snapshots; the difference reflects timing, not a discrepancy. (FHWA NBI 2024; ARTBA 2025)
NHDOT inspects municipal bridges free of charge, which is a meaningful subsidy for small towns that would otherwise need to hire consultants. Even so, the municipal bridge aid program in the 2025-2034 Ten Year Plan is now fully enrolled, meaning towns seeking state assistance for bridge projects face a queue with no open slots. (NHDOT)
Funding Math
New Hampshire's gas tax sat at $0.18 per gallon for 23 years before SB 367 raised it to $0.222 in 2014. That 4.2-cent increase generates roughly $32 to $34 million per year, and the gas tax accounts for approximately 55% of highway fund revenue. (NH Legislature; NHDOT)
The increase is temporary. SB 367 includes a statutory expiration: the 4.2-cent surcharge ends in 20 years or when the I-93 bonding is paid off, whichever comes first. This is not a sunset clause buried in fine print. It is the central constraint on New Hampshire's bridge funding trajectory, because the state has no other broad-based revenue tool to backfill the gap. The gas tax is not indexed to inflation. (NH Legislature)
Federal IIJA Bridge Formula Program funds total $225 million for New Hampshire. Of that, $180 million is currently accessible, and $59.9 million has been committed to 9 projects, a 33% commitment rate. The national average is 55%. (ARTBA; FHWA)
ARTBA estimates the total bridge repair backlog at $7.4 billion, calculated using FHWA 2023 average costs and a 68% rehabilitation-to-replacement ratio. The $225 million IIJA allocation is substantial for a state with 192 poor bridges but covers roughly 3% of the total estimated need. (ARTBA 2025)
Age and Climate
Approximately 80% of state-owned bridges in New Hampshire were built before 1980, according to an ASCE assessment using circa 2017 data. Average bridge age has reached or exceeded a typical 50-year design life, which means a growing share of the inventory is entering the period when deterioration accelerates and maintenance costs compound. (ASCE, c. 2017)
Climate is an accelerant, not the primary driver. The primary causes of New Hampshire's bridge deterioration are age, constrained funding, and the municipal ownership burden. Freeze-thaw cycling is aggressive across the state, and researchers have documented that midwinter thaw-refreeze events are increasing in frequency. Combined with heavy road salt use and chloride penetration of older decks that lack modern protective coatings, these conditions speed the deterioration of an already-aging inventory. (UNH; NHDOT)
Trajectory
The poor-bridge count dropped from 194 to 192 over four years, while the number of bridges needing some level of repair rose from 2,473 to 2,498. (ARTBA 2025) The Red List shows a similar pattern of slow net improvement. The state Red List count fell from 133 to 112 over a decade, and the municipal list has trended downward since 2017 after NHDOT adjusted the criteria. (NHDOT)
Among New England neighbors, Maine (15%) and Rhode Island (14%) carry worse poor-bridge rates, while Connecticut and Massachusetts sit at roughly 9%. All share old infrastructure and harsh winters, but New Hampshire's tax structure makes its revenue tools more limited than any of its regional peers. (ARTBA 2025)
NHS bridges on the major freight corridors (I-93, I-89, I-95) are in notably better shape: only 26 of 727 NHS bridges are rated poor, a 3.6% rate. (FHWA NBI 2024) The problem concentrates on older, smaller, locally owned structures off the national network.
The open question is whether New Hampshire can accelerate repairs before the broader inventory ages into poor condition. The IIJA funds are a window, with 33% committed so far against a national pace of 55%. The gas tax increase that funds much of the state match is temporary. The municipal bridge aid program is full. The Red List keeps getting shorter, which means the monitoring is working and the repair programs are producing results. Whether those results can outrun the aging curve with the most constrained revenue toolkit in the top 15 is the question the next decade will answer.
What "Poor Condition" Means
A bridge is classified as being in "poor condition" if any one of its three primary components (deck, superstructure, or substructure) receives a rating of 4 or below on the NBI's 0-to-9 scale. A poor rating does not mean a bridge is unsafe or at risk of collapse. It means the bridge has deteriorated to the point where it needs repair or replacement. Bridges rated poor are typically subject to increased inspection frequency, load restrictions, or both.
Data Sources
Statewide totals (2,549 bridges, 192 poor, 8%, rank #14) are from the ARTBA 2025 Bridge Report, based on FHWA National Bridge Inventory data. Ownership breakdowns are from the FHWA NBI 2024 dataset, which totals 2,542 bridges and 191 poor due to a slightly different data vintage. Red List figures (324 bridges: 112 state, 212 municipal) are from the NHDOT 2024 inspection cycle. The $7.4 billion backlog estimate is from ARTBA, using FHWA 2023 average costs and a 68% rehabilitation-to-replacement ratio. Gas tax and legislative data are from the New Hampshire Legislature and NHDOT.
Caveats
Bridge inspection practices and rating standards can vary by inspector and agency. The NBI captures a snapshot in time; individual bridge conditions change between inspection cycles. The Red List uses NHDOT criteria and includes sub-20-foot structures not reported in the NBI, which is why the Red List count (324) exceeds the ARTBA poor-bridge count (192). Percentages are rounded to whole numbers except for the national average (6.7%) and ownership table rates (5.8%, 9.6%, 5.4%, 12.5%, 20.0%), which retain published decimals.