County profile · official public datasets

Del Norte County, CA

96 public highway bridges tracked in the FHWA National Bridge Inventory: 51% rated Good, 37.5% Fair, 11.5% Poor.

96
Public bridges: 51%
Good condition: 11.5%
Poor condition

The verdict

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

Del Norte County pairs a higher-than-median Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

50th
of 58 on Poor share: 11.5%
Poor-condition share: 96
public highway bridges: 1975
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.

Del Norte County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Del Norte County ranks #50 of 58 California counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 11.5%). Del Norte County, California contains 96 public highway bridges. Roughly 51% are rated “Good,” 37.5% “Fair,” and 11.5% “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

Public highway bridges in Del Norte County

Good condition

51%

49 of 96 rated 7-9

Fair condition

37.5%

36 of 96 rated 5-6

Poor condition

11.5%

11 of 96 rated 4 or below

In-state Poor-share rank

#50 of 58

Among California counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 96 NBI-tracked bridges by lowest applicable component rating.

Good

51% (49)

Fair

37.5% (36)

Poor

11.5% (11)

Del Norte County's Poor-condition bridges carry 135 vehicle crossings a day

That is 0.1% of the county's reported daily bridge traffic on 11.5% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 12 crossings a day against 2,767 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 96 of 96 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

54.2% of Del Norte County's bridges have passed the 50-year mark

52 of the 96 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 51% 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 18.5% of the county's Poor-condition bridge traffic

HAMILTON ROAD over WEST BRANCH MILL CREEK, built 1950, carries 25 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 11-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 135 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1920s

2
1940s

5
1950s

21
1960s

16
1970s

17
1980s

11
1990s

4
2000s

9
2010s

8
2020s

3

What this shows Construction peaked in the 1950s, when 21 of the county's bridges still in the inventory were built, which is 21.9% of those with a recorded year. That cohort is now 65 to 74 years old in the 2024 inventory. Its average build year is 1975, 5 years newer than the California average of 1970.

How Del Norte County compares with California's closest counties by inventory size

The 5 California counties nearest Del Norte County in number of bridges, with their condition splits. Its 11.5% Poor share is the 6th-lowest of these 6. Its average build year of 1975 against a peer-group mean of 1965 is 10 years newer.

Showing the 5 closest of 57 California counties eligible for comparison.

Bridge inventory size and condition shares for Del Norte County and the 5 California counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Mariposa County	109	21.1%	67.9%	11%	1956
Lassen County	108	25.9%	65.7%	8.3%	1968
Calaveras County	105	33.3%	60%	6.7%	1962
Del Norte County (this page)	96	51%	37.5%	11.5%	1975
Modoc County	87	49.4%	49.4%	1.1%	1969
San Benito County	76	46.1%	43.4%	10.5%	1971

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 Del Norte 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 Del Norte County, both outside California so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside CA (96 bridges here).

Routt County, CO · 96 bridges
Blaine County, ID · 96 bridges
Clare County, MI · 96 bridges
Menominee County, MI · 96 bridges

Similar average build year

Nearest mean year-built outside CA (1975 here).

Lane County, OR · avg 1975 · 1,010 bridges
Fulton County, GA · avg 1975 · 775 bridges
Westmoreland County, PA · avg 1975 · 620 bridges
Monroe County, NY · avg 1975 · 615 bridges

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

All 96 Good 49 Fair 36 Poor 11

Fair-condition bridges (36)

Sort:

Del Norte County Bridge Snapshot

Condition distribution

Del Norte County's Poor-condition bridges carry 135 vehicle crossings a day

54.2% of Del Norte County's bridges have passed the 50-year mark

One structure carries 18.5% of the county's Poor-condition bridge traffic

How Del Norte County compares with California's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

Fair-condition bridges (36)

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HAMILTON ROAD

U.S. HIGHWAY 101

REQUA ROAD

MILL CREEK CMPGRND

OCEAN VIEW DRIVE

OLD GASQUET TOLL

BREEN MEMORIAL RD

U.S. HIGHWAY 101

REQUA ROAD

GASQUET FLAT ROAD

U.S. HIGHWAY 101

U.S. HIGHWAY 199

W169-N101 CONNECTR

COUNTY ROAD 316

U.S. HIGHWAY 101

US HIGHWAY 199 NB

US HIGHWAY 101 SB

US HIGHWAY 199 NB

SOUTH FORK ROAD

OREGON MOUNTAIN RD

U.S. HIGHWAY 101

U.S. HIGHWAY 101

WALKER ROAD

KLAMATH MILL ROAD

SOUTH FORK ROAD

S101-CHAPMAN ST RP

US HIGHWAY 199 NB

LAKE EARL DRIVE

U.S. HIGHWAY 101

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