County profile · official public datasets

Belknap County, NH

112 public highway bridges tracked in the FHWA National Bridge Inventory: 58% rated Good, 37.5% Fair, 4.5% Poor.

112
Public bridges: 58%
Good condition: 4.5%
Poor condition

The verdict

According to the Federal Highway Administration's 2024 National Bridge Inventory.

Belknap County posts a top-quartile lowest Poor-condition share among rated counties in the state across mid-size county bridge inventory.

Top 20%
lowest Poor share in state: 4.5%
Poor-condition share: 112
public highway bridges: 1969
avg year built

Poor is an FHWA condition category from the lowest applicable component rating (4 or below), not a live crossing-safety or closure decision. Rankings cover counties with at least five public highway bridges.

Belknap County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Belknap County ranks #2 of 10 New Hampshire counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 4.5%). Belknap County, New Hampshire contains 112 public highway bridges. Roughly 58% are rated “Good,” 37.5% “Fair,” and 4.5% “Poor.” Poor means the lowest applicable deck, superstructure, substructure, or culvert rating is 4 or below on the 0–9 NBI scale. It is a condition category, not a live safety or closure decision.

Responsible agencies inspect covered bridges on risk-based intervals under current NBIS rules and submit inventory data to FHWA annually. The list below shows every NBI-tracked bridge in the county. Use the “Sort by” controls to change the ordering, and click any row for its reported inspection date, traffic count, and condition fields.

Source: FHWA National Bridge Inventory. See methodology for full definitions.

Total bridges

112

Public highway bridges in Belknap County

Good condition

58%

65 of 112 rated 7-9

Fair condition

37.5%

42 of 112 rated 5-6

Poor condition

4.5%

5 of 112 rated 4 or below

In-state Poor-share rank

#2 of 10

Among New Hampshire counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 112 NBI-tracked bridges by lowest applicable component rating.

Good

58% (65)

Fair

37.5% (42)

Poor

4.5% (5)

Belknap County's Poor-condition bridges carry 18,477 vehicle crossings a day

That is 3% of the county's reported daily bridge traffic on 4.5% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 3,695 crossings a day against 4,380 for a Good-condition one. A Poor rating is a condition category, not a closure or a live safety judgement; it means the lowest applicable component rating is 4 or below.

Computed over the 112 of 112 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

62.5% of Belknap County's bridges have passed the 50-year mark

70 of the 112 bridges with a recorded construction year were built in 1974 or earlier. Age alone is not a defect: a well-maintained older bridge can rate Good, and 58% of this county's inventory does. Even so, this older cohort is the population from which future Poor ratings are drawn, which is why the age profile below matters alongside the condition split above.

Cutoff derives from the 2024 release year minus a 50-year design life. Source: FHWA National Bridge Inventory, 2024 release.

One structure carries 55.2% of the county's Poor-condition bridge traffic

NH 11 over MERRYMEETING RIVER, built 1934, carries 10,193 vehicles a day, the most of any Poor-rated structure here. The county's Poor-condition exposure is concentrated rather than evenly spread, so the 5-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 18,477 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

3
1920s

8
1930s

9
1940s

9
1950s

3
1960s

33
1970s

8
1980s

9
1990s

6
2000s

9
2010s

9
2020s

6

What this shows Construction peaked in the 1960s, when 33 of the county's bridges still in the inventory were built, which is 29.5% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1969) matches the New Hampshire average (1968).

How Belknap County compares with New Hampshire's closest counties by inventory size

The 5 New Hampshire counties nearest Belknap County in number of bridges, with their condition splits. Its 4.5% Poor share is the 2nd-lowest of these 6. Its average build year of 1969 against a peer-group mean of 1965 is in line with the group.

Showing the 5 closest of 9 New Hampshire counties eligible for comparison.

Bridge inventory size and condition shares for Belknap County and the 5 New Hampshire counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Carroll County	193	54.9%	40.9%	4.1%	1966
Cheshire County	192	41.7%	46.9%	11.5%	1960
Coos County	188	49.5%	44.1%	6.4%	1964
Sullivan County	158	45.6%	49.4%	5.1%	1963
Strafford County	136	63.2%	27.9%	8.8%	1971
Belknap County (this page)	112	58%	37.5%	4.5%	1969

Each share is of that county's own total tracked bridges; peers are the counties with 5 or more bridges whose inventory size is closest to Belknap County's. Source: FHWA National Bridge Inventory, 2024 release.

Nationwide counties with similar inventory size or average build year

Two NBI-derived peer sets for Belknap County, both outside New Hampshire so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside NH (112 bridges here).

Columbia County, FL · 112 bridges
Sumter County, FL · 112 bridges
Houston County, GA · 112 bridges
Tift County, GA · 112 bridges

Similar average build year

Nearest mean year-built outside NH (1969 here).

Cook County, IL · avg 1969 · 1,721 bridges
Fresno County, CA · avg 1969 · 916 bridges
Cuyahoga County, OH · avg 1969 · 871 bridges
Ventura County, CA · avg 1969 · 501 bridges

Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.

All 112 Good 65 Fair 42 Poor 5

All bridges (112)

Sort:

Belknap County Bridge Snapshot

Condition distribution

Belknap County's Poor-condition bridges carry 18,477 vehicle crossings a day

62.5% of Belknap County's bridges have passed the 50-year mark

One structure carries 55.2% of the county's Poor-condition bridge traffic

How Belknap County compares with New Hampshire's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

All bridges (112)

NARROWS ROAD

DEPOT ROAD

HARTSHORN ROAD

US 3 BUS NH107

US 3 NH 11

NH 11

OXBOW ROAD

PARADE HILL ROAD

NH 11

US 3

NH 11B

NH 11A

MESSER STREET

NH140

HANNAH NUTTER ROAD

GOVNRS ISLAND RD

I-93 NB

I-93 SB

I-93 SB

I-93 NB

I-93 SB

US 3 NH 11

I-93 SB

NH 28

NH140

HENDERSON ROAD

US 3 NH 11

I-93 SB

I-93 NB

NH106 MAIN ST

PRESCOTT ROAD

US 3 NH 11 NH132

CRYSTAL LAKE ROAD

US 3 BUS NH107

JAMESTOWN ROAD

PINNACLE HILL ROAD

ALVAH WILSON ROAD

SCHOOL STREET

NH 11A

I-93 NB

I-93 SB

US 3

NH106

CRYSTAL LAKE ROAD

MORRILL STREET

HERMIT WOODS ROAD

NH126

NH 11

I-93 NB

COOLIDGE WOODS RD

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