County profile · official public datasets

Mason County, WA

133 public highway bridges tracked in the FHWA National Bridge Inventory: 53.4% rated Good, 42.1% Fair, 4.5% Poor.

133
Public bridges: 53.4%
Good condition: 4.5%
Poor condition

The verdict

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

Mason County posts a better-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.

Top 44%
lowest Poor share in state: 4.5%
Poor-condition share: 133
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.

Mason County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Mason County ranks #17 of 39 Washington counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 4.5%). Mason County, Washington contains 133 public highway bridges. Roughly 53.4% are rated “Good,” 42.1% “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

133

Public highway bridges in Mason County

Good condition

53.4%

71 of 133 rated 7-9

Fair condition

42.1%

56 of 133 rated 5-6

Poor condition

4.5%

6 of 133 rated 4 or below

In-state Poor-share rank

#17 of 39

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

Condition distribution

Share of 133 NBI-tracked bridges by lowest applicable component rating.

Good

53.4% (71)

Fair

42.1% (56)

Poor

4.5% (6)

Mason County's Poor-condition bridges carry 21,118 vehicle crossings a day

That is 5.1% of the county's reported daily bridge traffic on 4.5% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 3,520 crossings a day against 2,221 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 133 of 133 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

55.6% of Mason County's bridges have passed the 50-year mark

74 of the 133 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 53.4% 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 83.5% of the county's Poor-condition bridge traffic

US 101 over MATLOCK RD, built 1973, carries 17,635 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 6-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 21,118 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1910s

1
1920s

9
1930s

2
1940s

2
1950s

21
1960s

29
1970s

15
1980s

10
1990s

14
2000s

16
2010s

9
2020s

5

What this shows Construction peaked in the 1960s, when 29 of the county's bridges still in the inventory were built, which is 21.8% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1975) matches the Washington average (1975).

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

The 5 Washington counties nearest Mason 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 1975 against a peer-group mean of 1974 is in line with the group.

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

Bridge inventory size and condition shares for Mason County and the 5 Washington counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Clallam County	151	56.3%	37.7%	6%	1979
Chelan County	149	57.7%	34.2%	8.1%	1974
Franklin County	134	56%	39.6%	4.5%	1970
Mason County (this page)	133	53.4%	42.1%	4.5%	1975
Pacific County	120	56.7%	37.5%	5.8%	1974
Skamania County	120	45.8%	45%	9.2%	1974

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

Similar inventory size

Nearest county inventories outside WA (133 bridges here).

Henry County, AL · 133 bridges
Nevada County, AR · 133 bridges
Gordon County, GA · 133 bridges
East Feliciana County, LA · 133 bridges

Similar average build year

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

San Bernardino County, CA · avg 1975 · 1,422 bridges
Lane County, OR · avg 1975 · 1,010 bridges
Fulton County, GA · avg 1975 · 775 bridges
Westmoreland County, PA · avg 1975 · 620 bridges

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

All 133 Good 71 Fair 56 Poor 6

Good-condition bridges (71)

Sort:

Mason County Bridge Snapshot

Condition distribution

Mason County's Poor-condition bridges carry 21,118 vehicle crossings a day

55.6% of Mason County's bridges have passed the 50-year mark

One structure carries 83.5% of the county's Poor-condition bridge traffic

How Mason 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 (71)

Eckert Road

US 101

Skokomish ValleyRd

Shelton Matlock Rd

Little Egypt Rd

Deckerville Road

SR 3

Mission Creek Rd

Skokomish Valley R

US 101

Skokomish Valley R

Shelton Matlock Rd

Beeville Road

Old Belfair Highwa

Schaffer St Prk Rd

US 101

7TH AVENUE

BEEVILLE LOOP

NO DATA ENTERED

NO DATA ENTERED

US 101

NO DATA ENTERED

NO DATA ENTERED

NO DATA ENTERED

US 101

NO DATA ENTERED

C ST

SR 106

NO DATA ENTERED

SHELTON-MATLOCK RD

NO DATA ENTERED

Skokomish ValleyRD

US 101 S-N RAMP

Schaffer Park Rd

BEAR CR - DEWATTO

Deegan Road West

NO DATA ENTERED

SR 106

NO DATA ENTERED

Elfendahl Pass Rd

Mason Lake Rd.

Eich Road

Old Oly. Highway

Finch Creek Rd

W. KNEELAND BLVD

US 101

IRR BIA RTE 8

Cloquallum Road

SR 108

SKOK. RIVER RD

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