County profile · official public datasets

Marion County, OR

373 public highway bridges tracked in the FHWA National Bridge Inventory: 21.2% rated Good, 74.5% Fair, 4.3% Poor.

373
Public bridges: 21.2%
Good condition: 4.3%
Poor condition

The verdict

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

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

22nd
of 36 on Poor share: 4.3%
Poor-condition share: 373
public highway bridges: 1971
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.

Marion County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Marion County ranks #22 of 36 Oregon counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 4.3%). Marion County, Oregon contains 373 public highway bridges. Roughly 21.2% are rated “Good,” 74.5% “Fair,” and 4.3% “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

373

Public highway bridges in Marion County

Good condition

21.2%

79 of 373 rated 7-9

Fair condition

74.5%

278 of 373 rated 5-6

Poor condition

4.3%

16 of 373 rated 4 or below

In-state Poor-share rank

#22 of 36

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

Condition distribution

Share of 373 NBI-tracked bridges by lowest applicable component rating.

Good

21.2% (79)

Fair

74.5% (278)

Poor

4.3% (16)

Marion County's Poor-condition bridges carry 52,460 vehicle crossings a day

That is 1.3% of the county's reported daily bridge traffic on 4.3% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 3,279 crossings a day against 8,093 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 373 of 373 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

61.7% of Marion County's bridges have passed the 50-year mark

230 of the 373 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 21.2% 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 21.7% of the county's Poor-condition bridge traffic

SCOTTS MILLS RD over BUTTE CREEK, built 1947, carries 11,400 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 16-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 52,460 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1910s

4
1920s

20
1930s

14
1940s

7
1950s

68
1960s

84
1970s

56
1980s

27
1990s

32
2000s

44
2010s

15
2020s

2

What this shows Construction peaked in the 1960s, when 84 of the county's bridges still in the inventory were built, which is 22.5% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1971) matches the Oregon average (1975).

How Marion County compares with Oregon's closest counties by inventory size

The 5 Oregon counties nearest Marion County in number of bridges, with their condition splits. Its 4.3% Poor share is the 6th-lowest of these 6. Its average build year of 1971 against a peer-group mean of 1975 is in line with the group.

Showing the 5 closest of 35 Oregon counties eligible for comparison.

Bridge inventory size and condition shares for Marion County and the 5 Oregon counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Multnomah County	473	11.8%	85.2%	3%	1967
Jackson County	401	34.2%	64.3%	1.5%	1976
Marion County (this page)	373	21.2%	74.5%	4.3%	1971
Clackamas County	367	31.1%	66.5%	2.5%	1975
Washington County	326	35.6%	62%	2.5%	1983
Umatilla County	321	31.5%	64.5%	4%	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 Marion 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 Marion County, both outside Oregon so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside OR (373 bridges here).

Solano County, CA · 373 bridges
Hunterdon County, NJ · 373 bridges
Benton County, IA · 374 bridges
Baltimore city County, MD · 374 bridges

Similar average build year

Nearest mean year-built outside OR (1971 here).

Wayne County, MI · avg 1971 · 1,026 bridges
Baltimore County, MD · avg 1971 · 783 bridges
Washington County, PA · avg 1971 · 655 bridges
Monmouth County, NJ · avg 1971 · 505 bridges

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

All 373 Good 79 Fair 278 Poor 16

Fair-condition bridges (278)

Sort:

Marion County Bridge Snapshot

Condition distribution

Marion County's Poor-condition bridges carry 52,460 vehicle crossings a day

61.7% of Marion County's bridges have passed the 50-year mark

One structure carries 21.7% of the county's Poor-condition bridge traffic

How Marion County compares with Oregon'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 (278)

I-5 (Hwy 1) NB

DOMINIC ROAD

DELANEY RD SE

OR 214 (HWY 140)

Golf Club Road

WINDSOR ISLAND RD

WINTER ST NE

I-5 (Hwy 1) NB

I-5 (Hwy 1) SB

I-5 (Hwy 1)

I-5 (Hwy 1)

JETTERS WAY

SO. ABIQUA RD.

I-5 (Hwy 1) Fr Rd

I-5 (Hwy 1) SB

Waconda Road

I-5 (Hwy 1) NB

KUEBLER BLVD

N.THIRD AVE

I-5 (Hwy 1) NB

I-5 (Hwy 1) SB

I-5 (Hwy 1) NB

I-5 (Hwy 1) SB

I-5 (Hwy 1) NB

I-5 (Hwy 1) SB

AUMSVILLE HWY

SUMMER STREET NE

TURNER RD

NUSOM ROAD

TEETERS RD

I-5 (Hwy 1)

SARATOGA DR SE.

KAUFMAN RD

KAUFMAN RD

Crosby Road

RAVENA DRIVE

FERN RIDGE RD

I-5 (Hwy 1) NB

I-5 (Hwy 1)

25TH ST SE

CHAMPOEG RD

OR 214 (Hwy 140)

I-5 (Hwy 1)

Donald Road

09 S 03 E 11.03:

W WASH ST

I-5 (Hwy 1) Conn.

OR 22 (Hwy 72)

St. Louis Road

Kuebler Rd.

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