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.

When Mason County's bridges were built

133 bridges with a recorded construction year, grouped by decade

bridges

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).

Source FHWA National Bridge Inventory (year built) As of 2024 NBI release

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 Poor
Clallam County 151 6%
Chelan County 149 8.1%
Franklin County 134 4.5%
Mason County (this page) 133 4.5%
Pacific County 120 5.8%
Skamania County 120 9.2%

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).

Similar average build year

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

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

All bridges (133)

Shelton Matlock Rd

Fair

Over: NO. FORK GOLDSBOROUGH CK

0.23 E Dayton Airport rd, Mason, WA

Built 1988 Load: 49.0 t ADT: 1,777

E. Mason Lake Rd W

Fair

Over: SCHUMOCHER CREEK

0.73 MI NO OF Mason LK Rd, Mason, WA

Built 2002 Load: 50.8 t ADT: 490

NO DATA ENTERED

Fair

Over: TRIB. TO CANYON RIVER

NO DATA ENTERED, Mason, WA

Built 2004 Load: 54.9 t ADT: 50

W CLOQUALLUM RD

Fair

Over: US 101

4.5 S JCT SR 102, Mason, WA

Built 1972 Load: 63.5 t ADT: 1,207

NO DATA ENTERED

Fair

Over: ROCK CK.

NO DATA ENTERED, Mason, WA

Built 1975 Load: 97.2 t ADT: 50

NO DATA ENTERED

Fair

Over: SNOW CREEK

NO DATA ENTERED, Mason, WA

Built 2010 Load: 97.2 t ADT: 50

Eckert Road

Good

Over: CASE INLET

0.15 E Grapeview Loop rd, Mason, WA

Built 1920 Load: 13.6 t ADT: 385

US 101

Good

Over: HAMMA HAMMA RIVER

5.3 S JEFFERSON CO, Mason, WA

Built 1924 Load: 16.5 t ADT: 2,489

Skokomish ValleyRd

Good

Over: VANCE CREEK

3.88 W JCT SR 101, Mason, WA

Built 1963 Load: 17.2 t ADT: 494

Shelton Matlock Rd

Good

Over: GOLDSBOROUGH CREEK

4.85 W JCT SR 3, Mason, WA

Built 1956 Load: 17.8 t ADT: 2,079

Little Egypt Rd

Good

Over: SO. FK. GOLDSBOROUGH CK.

1.86 S SheltonMatlock Rd, Mason, WA

Built 1966 Load: 19.0 t ADT: 191

Deckerville Road

Good

Over: DRY BED CREEK

0.59 W JCT Matlock, Mason, WA

Built 1963 Load: 20.9 t ADT: 149

SR 3

Good

Over: DEER CREEK

9.0 N JCT US 101, Mason, WA

Built 1957 Load: 22.7 t ADT: 15,491

Mission Creek Rd

Good

Over: MISSION CREEK

0.40 N JCT SR 300, Mason, WA

Built 1991 Load: 22.7 t ADT: 827

Skokomish Valley R

Good

Over: VANCE CREEK

4.58 W JCT SR101, Mason, WA

Built 1959 Load: 24.5 t ADT: 494

US 101

Good

Over: MILL CREEK

4.9 S JCT SR 102, Mason, WA

Built 1973 Load: 24.9 t ADT: 18,814

Skokomish Valley R

Good

Over: VANCE CREEK

6.19 m W SR 101, Mason, WA

Built 1986 Load: 25.4 t ADT: 110

Shelton Matlock Rd

Good

Over: BINGHAM CREEK

1.3 E MATLOCK, Mason, WA

Built 1960 Load: 25.4 t ADT: 1,437

Beeville Road

Good

Over: DRY BED CREEK

4 Miles N of Matlock, Mason, WA

Built 1984 Load: 25.4 t ADT: 16

Old Belfair Highwa

Good

Over: UNION RIVER

1.19 N JCT SR 300, Mason, WA

Built 1987 Load: 26.3 t ADT: 3,517

Schaffer St Prk Rd

Good

Over: DECKER CREEK

0.59 E JCT MatlockBrady, Mason, WA

Built 1967 Load: 26.3 t ADT: 376

US 101

Good

Over: EAGLE CR

10.1 S JEFFERSON CO, Mason, WA

Built 1950 Load: 26.9 t ADT: 2,944

7TH AVENUE

Good

Over: GOLDSBROUGH CREEK

00.1 S RAILROAD AVE, Mason, WA

Built 1976 Load: 27.2 t ADT: 6,000

BEEVILLE LOOP

Good

Over: RABBIT CREEK

BEEVILLE LOOP, Mason, WA

Built 2010 Load: 27.2 t ADT: 32

NO DATA ENTERED

Good

Over: WALTER CREEK

NO DATA ENTERED, Mason, WA

Built 1967 Load: 28.1 t ADT: 25

NO DATA ENTERED

Good

Over: PINE CREEK

NO DATA ENTERED, Mason, WA

Built 1959 Load: 28.1 t ADT: 25

US 101

Good

Over: FINCH CREEK

17.1 S JEFFERSON CO, Mason, WA

Built 1925 Load: 28.8 t ADT: 4,404

NO DATA ENTERED

Good

Over: LAKE CUSHMAN (N FK SKOK)

N.W. END OF LAKE CUSHMAN, Mason, WA

Built 1959 Load: 30.0 t ADT: 5

NO DATA ENTERED

Good

Over: BAKER CREEK

NO DATA ENTERED, Mason, WA

Built 1964 Load: 30.9 t ADT: 15

NO DATA ENTERED

Good

Over: JEFFERSON CREEK

NO DATA ENTERED, Mason, WA

Built 1975 Load: 30.9 t ADT: 10

US 101

Good

Over: WEAVER CREEK

2.1 S JCT SR 106, Mason, WA

Built 1970 Load: 31.8 t ADT: 7,382

NO DATA ENTERED

Good

Over: LAKE CUSHMAN (N FK SKOK)

N.W. END OF LAKE CUSHMAN, Mason, WA

Built 2011 Load: 32.4 t ADT: 5

C ST

Good

Over: US 101

2.8 S JCT SR 102, Mason, WA

Built 1973 Load: 32.7 t ADT: 1,270

SR 106

Good

Over: TWANOH CREEK

12.3 E JCT US 101, Mason, WA

Built 2023 Load: 32.8 t ADT: 2,309

NO DATA ENTERED

Good

Over: BROWN CREEK

NO DATA ENTERED, Mason, WA

Built 1969 Load: 36.3 t ADT: 75

SHELTON-MATLOCK RD

Good

Over: COFFEE CREEK

3.6 S JCT SR 102, Mason, WA

Built 2020 Load: 36.6 t ADT: 1,000

NO DATA ENTERED

Good

Over: LEBAR CREEK

NO DATA ENTERED, Mason, WA

Built 1974 Load: 37.2 t ADT: 25

Skokomish ValleyRD

Good

Over: HUNTER CREEK

1.76 W JCT SR 101, Mason, WA

Built 2015 Load: 37.9 t ADT: 494

US 101 S-N RAMP

Good

Over: WETLAND

5.7 S JCT SR 102, Mason, WA

Built 2008 Load: 38.1 t ADT: 1,151

Schaffer Park Rd

Good

Over: EAST FORK SATSOP RIVER

1.29 E Matlock Brady rd, Mason, WA

Built 1993 Load: 38.1 t ADT: 376

BEAR CR - DEWATTO

Good

Over: DEWATTO RIVER

9.56 W OF BELFAIR HWY, Mason, WA

Built 2008 Load: 38.1 t ADT: 79

Deegan Road West

Good

Over: Coffee Creek

2.35 E Shelton Matlock Rd, Mason, WA

Built 2020 Load: 38.1 t ADT: 187

NO DATA ENTERED

Good

Over: UPPER CANYON RIVER

NO DATA ENTERED, Mason, WA

Built 1955 Load: 38.5 t ADT: 15

SR 106

Good

Over: TWANOH FALLS CREEK

13.5 E JCT US 101, Mason, WA

Built 2014 Load: 38.9 t ADT: 2,309

NO DATA ENTERED

Good

Over: HAMMA HAMMA RIVER

NO DATA ENTERED, Mason, WA

Built 1968 Load: 39.0 t ADT: 25

Elfendahl Pass Rd

Good

Over: Stimson Creek

0.17 N JCT N. Shore rd, Mason, WA

Built 2013 Load: 39.5 t ADT: 65

Mason Lake Rd.

Good

Over: CRANBERRY CREEK

2.68 N JCT SR 3, Mason, WA

Built 1993 Load: 39.9 t ADT: 1,783

Eich Road

Good

Over: Little Skookum Creek

0.15 N Jct SR 108, Mason, WA

Built 2004 Load: 39.9 t ADT: 22

Old Oly. Highway

Good

Over: SKOOKUM CREEK

0.43 S JCT SR101, Mason, WA

Built 2006 Load: 39.9 t ADT: 72

Finch Creek Rd

Good

Over: FINCH CREEK

0.18 Miles W SR 101, Mason, WA

Built 2009 Load: 39.9 t ADT: 184

Read our methodology - how this data is sourced, computed, and verified.

Related

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Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainBridges

Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.