County profile · official public datasets

Whatcom County, WA

354 public highway bridges tracked in the FHWA National Bridge Inventory: 44.1% rated Good, 50.6% Fair, 5.4% Poor.

354
Public bridges: 44.1%
Good condition: 5.4%
Poor condition

The verdict

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

Whatcom County pairs a better-than-median Poor-condition share among rated counties in the state with an older average build year than the state inventory.

Top 49%
lowest Poor share in state: 5.4%
Poor-condition share: 354
public highway bridges: 1970
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.

Whatcom County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Whatcom County ranks #19 of 39 Washington counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 5.4%). Whatcom County, Washington contains 354 public highway bridges. Roughly 44.1% are rated “Good,” 50.6% “Fair,” and 5.4% “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

354

Public highway bridges in Whatcom County

Good condition

44.1%

156 of 354 rated 7-9

Fair condition

50.6%

179 of 354 rated 5-6

Poor condition

5.4%

19 of 354 rated 4 or below

In-state Poor-share rank

#19 of 39

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

Condition distribution

Share of 354 NBI-tracked bridges by lowest applicable component rating.

Good

44.1% (156)

Fair

50.6% (179)

Poor

5.4% (19)

Whatcom County's Poor-condition bridges carry 74,479 vehicle crossings a day

That is 4% of the county's reported daily bridge traffic on 5.4% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 3,920 crossings a day against 5,178 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 354 of 354 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

61.9% of Whatcom County's bridges have passed the 50-year mark

219 of the 354 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 44.1% 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 13.4% of the county's Poor-condition bridge traffic

SR 544 over NOOKSACK R OVERFLOW, built 1994, carries 9,956 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 19-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 74,479 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

6
1910s

2
1920s

8
1930s

35
1940s

32
1950s

71
1960s

49
1970s

25
1980s

19
1990s

25
2000s

47
2010s

25
2020s

10

What this shows Construction peaked in the 1950s, when 71 of the county's bridges still in the inventory were built, which is 20.1% of those with a recorded year. That cohort is now 65 to 74 years old in the 2024 inventory. Its average build year is 1970, 5 years older than the Washington average of 1975.

How Whatcom County compares with Washington's closest counties by inventory size

The 5 Washington counties nearest Whatcom County in number of bridges, with their condition splits. Its 5.4% Poor share is the 3rd-lowest of these 6. Its average build year of 1970 against a peer-group mean of 1975 is 5 years older.

Showing the 5 closest of 38 Washington counties eligible for comparison.

Bridge inventory size and condition shares for Whatcom County and the 5 Washington counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Grays Harbor County	363	48.8%	41.9%	9.4%	1978
Whatcom County (this page)	354	44.1%	50.6%	5.4%	1970
Whitman County	347	52.2%	44.4%	3.5%	1974
Kittitas County	308	39%	50.6%	10.4%	1973
Spokane County	307	51.1%	42%	6.8%	1978
Grant County	306	63.7%	33.7%	2.6%	1973

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 Whatcom 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 Whatcom County, both outside Washington so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside WA (354 bridges here).

Hendricks County, IN · 355 bridges
Cameron County, TX · 355 bridges
Union County, NC · 353 bridges
Burlington County, NJ · 356 bridges

Similar average build year

Nearest mean year-built outside WA (1970 here).

Hamilton County, OH · avg 1970 · 783 bridges
Yavapai County, AZ · avg 1970 · 543 bridges
Garfield County, OK · avg 1970 · 504 bridges
San Luis Obispo County, CA · avg 1970 · 401 bridges

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

All 354 Good 156 Fair 179 Poor 19

Good-condition bridges (156)

Sort:

Whatcom County Bridge Snapshot

Condition distribution

Whatcom County's Poor-condition bridges carry 74,479 vehicle crossings a day

61.9% of Whatcom County's bridges have passed the 50-year mark

One structure carries 13.4% of the county's Poor-condition bridge traffic

How Whatcom County compares with Washington's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

Good-condition bridges (156)

Aaron Drive

SQUALICUM PKWY

SR 539

SR 542

N 14TH STREET

SR 542

MITCHELL AVE

ROAD

NO DATA ENTERED

NO DATA ENTERED

PORTAL WAY

I-5

ROAD

SR 11

MOSQUITO LK RD

OAT COLES RD

CUSTER SCHOOL RD

HUGHES AVE

SR 542

NB SR 539

CANYON CREEK #31

I-5

WICKERSHAM RD

SR 542

SR 542

SR 20

SR 542

SMITH RD

NB I-5

BADGER RD W

SR 542

LINDSAY RD

I-5

SR 20

SR 539

SR 539

ROAD #31

LOOMIS TRAIL RD

ROAD

NOOKSACK RD

NORTHSHORE RD

17th Ave.

SR 542

SAMISH WAY

BENDER RD

POTTER RD

SLATER RD

STATE ST ELLIS ST

I-5

SB SR 539

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