County profile · official public datasets

Ontonagon County, MI

64 public highway bridges tracked in the FHWA National Bridge Inventory: 37.5% rated Good, 46.9% Fair, 15.6% Poor.

64
Public bridges
37.5%
Good condition
15.6%
Poor condition

The verdict

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

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

60th
of 83 on Poor share
15.6%
Poor-condition share
64
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.

Ontonagon County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Ontonagon County ranks #60 of 83 Michigan counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 15.6%). Ontonagon County, Michigan contains 64 public highway bridges. Roughly 37.5% are rated “Good,” 46.9% “Fair,” and 15.6% “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

64

Public highway bridges in Ontonagon County

Good condition

37.5%

24 of 64 rated 7-9

Fair condition

46.9%

30 of 64 rated 5-6

Poor condition

15.6%

10 of 64 rated 4 or below

In-state Poor-share rank

#60 of 83

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

Condition distribution

Share of 64 NBI-tracked bridges by lowest applicable component rating.

Good
37.5% (24)
Fair
46.9% (30)
Poor
15.6% (10)

Ontonagon County's Poor-condition bridges carry 8,943 vehicle crossings a day

That is 15.2% of the county's reported daily bridge traffic on 15.6% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 894 crossings a day against 723 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 64 of 64 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

59.4% of Ontonagon County's bridges have passed the 50-year mark

38 of the 64 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 37.5% 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 20.6% of the county's Poor-condition bridge traffic

M-28 over WAPATO CREEK, built 1938, carries 1,845 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 10-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 8,943 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Ontonagon County's bridges were built

64 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1960s, when 13 of the county's bridges still in the inventory were built, which is 20.3% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year is 1970, 6 years older than the Michigan average of 1976.

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

How Ontonagon County compares with Michigan's closest counties by inventory size

The 5 Michigan counties nearest Ontonagon County in number of bridges, with their condition splits. Its 15.6% Poor share is the 5th-lowest of these 6. Its average build year of 1970 against a peer-group mean of 1978 is 8 years older.

Showing the 5 closest of 82 Michigan counties eligible for comparison.

Bridge inventory size and condition shares for Ontonagon County and the 5 Michigan counties closest to it in inventory size
County Bridges Poor
Mason County 66 7.6%
Newaygo County 65 10.8%
Wexford County 64 6.3%
Ontonagon County (this page) 64 15.6%
Gladwin County 63 6.3%
Mackinac County 63 19%

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

Similar inventory size

Nearest county inventories outside MI (64 bridges here).

Similar average build year

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

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

All 64 Good 24 Fair 30 Poor 10

All bridges (64)

FOREST ROAD 5250

Fair

Over: M BR ONTONAGON RIVER

6 MI N 5 MI E OF WATERSM, Ontonagon, MI

Built 1954 Load: 13.0 t ADT: 50

US-45

Fair

Over: E BR OF ONTONAGON RIVER

2.0 MI S OF M-26, Ontonagon, MI

Built 1958 Load: 19.8 t ADT: 1,540

FOREST ROAD 400

Fair

Over: CASCADE CREEK

4 MI N 5 MI E OF BERGLAND, Ontonagon, MI

Built 1963 Load: 21.1 t ADT: 50

FOREST ROAD 6930

Fair

Over: CISCO BR ONTONAGON RIVER

8 MI W OF PAULDING, Ontonagon, MI

Built 1951 Load: 21.1 t ADT: 50

M-28

Fair

Over: MATCH CREEK BURIED

8.6 MI W OF US-45, Ontonagon, MI

Built 1936 Load: 25.9 t ADT: 1,331

M-64 & M-38

Fair

Over: ONTONAGON R RIVER RD RR

ONTONAGON, Ontonagon, MI

Built 2005 Load: 27.5 t ADT: 3,625

M-64

Fair

Over: MINERAL RIVER

1.0 MI NE OF M-107, Ontonagon, MI

Built 1941 Load: 31.1 t ADT: 875

M-64

Fair

Over: HALFWAY CREEK

5.5 MI NE OF M-107, Ontonagon, MI

Built 1968 Load: 32.4 t ADT: 1,032

US-45

Fair

Over: BALTIMORE RIVER

7.4 MI N OF M-28, Ontonagon, MI

Built 1934 Load: 33.0 t ADT: 1,122

SLEEPY HOLLOW FH54

Fair

Over: BLUFF CREEK

9 MI S OF BRUCE CROSSING, Ontonagon, MI

Built 1985 Load: 33.6 t ADT: 100

M-64

Fair

Over: MINERAL RIVER

6.7 MI S OF M-107, Ontonagon, MI

Built 1939 Load: 33.7 t ADT: 1,175

M-64

Fair

Over: WEIGELS CREEK

2.9 MI SW OF US-45, Ontonagon, MI

Built 1945 Load: 36.3 t ADT: 2,117

KITZMAN ROAD

Fair

Over: MILL CREEK DIAMOND CREEK

1 MI N OF M-28, Ontonagon, MI

Built 1993 Load: 36.3 t ADT: 25

M-64

Fair

Over: POTATO RIVER

3.6 MI SW OF US-45, Ontonagon, MI

Built 1952 Load: 36.6 t ADT: 2,025

M-28

Fair

Over: M BR ONTONAGON RIVER

5.0 MI W OF HOUGHTON COL, Ontonagon, MI

Built 1929 Load: 36.6 t ADT: 2,303

M-64

Fair

Over: TOWNLINE CREEK

6.3 MI NE OF M-107, Ontonagon, MI

Built 1968 Load: 36.9 t ADT: 1,032

M-28 M-64

Fair

Over: MERRYWEATHER CREEK

0.1 MI E OF W JET M-64, Ontonagon, MI

Built 1932 Load: 37.6 t ADT: 2,120

M-64

Fair

Over: CRANBERRY RIVER

5.2 MI SW OF US-45, Ontonagon, MI

Built 1948 Load: 39.5 t ADT: 2,117

FOREST ROAD 360

Fair

Over: IRON RIVER

6 MI N 4 MI W OF BERGLAND, Ontonagon, MI

Built 1972 Load: 44.7 t ADT: 50

M-38

Fair

Over: FLINTSTEEL RIVER

4.0 MI NW OF GREENLAND, Ontonagon, MI

Built 1971 Load: 47.6 t ADT: 1,311

NORWICH ROAD FH53

Fair

Over: W BR ONTONAGON RIVER

15 MI S OF ONTONAGON, Ontonagon, MI

Built 1994 Load: 49.1 t ADT: 110

M-64

Fair

Over: MINERAL RIVER

4.6 MI S OF M-107, Ontonagon, MI

Built 1954 Load: 50.5 t ADT: 948

M-64

Fair

Over: LITTLE CRANBERRY RIVER

5.8 MI SW OF US-45, Ontonagon, MI

Built 1948 Load: 51.8 t ADT: 1,032

VICTORIA ROAD

Fair

Over: ONTONAGON RIVER

1.8 MI SW OF ROCKLAND, Ontonagon, MI

Built 1977 Load: 55.8 t ADT: 150

US-45

Fair

Over: ROSELAWN CREEK

5.2 MI N OF GOGEBIC COL, Ontonagon, MI

Built 1957 Load: 56.4 t ADT: 1,700

LAKESHORE DRIVE

Fair

Over: FIRESTEEL RIVER

6 MI NE OF OTONAGON, Ontonagon, MI

Built 1976 Load: 85.5 t ADT: 120

US-45

Fair

Over: CLEAR CREEK

1.7 MI S BRUCE CROSSING, Ontonagon, MI

Built 1963 Load: 97.2 t ADT: 1,648

US-45

Fair

Over: CLEAR CREEK

1.2 MI S BRUCE CROSSING, Ontonagon, MI

Built 1963 Load: 97.2 t ADT: 1,122

US-45

Fair

Over: CLEAR CREEK

0.9 MI S BRUCE CROSSING, Ontonagon, MI

Built 1963 Load: 97.2 t ADT: 1,648

GARDNER ROAD FH55

Fair

Over: TROUT CREEK

3 MI N OF TROUT CREEK, Ontonagon, MI

Built 1982 Load: 97.2 t ADT: 180

LAKE SHORE ROAD

Good

Over: PADDYS CREEK

0.5 MI E OF ONTONAGON, Ontonagon, MI

Built 1976 Load: 31.8 t ADT: 240

NORWICH ROAD FH53

Good

Over: DEER CREEK

8 MI S OF ONTONAGON, Ontonagon, MI

Built 1987 Load: 32.7 t ADT: 150

HOOP AND HOLLER RD

Good

Over: MERRIWEATHER CREEK

3 MI S OF MERRIWEATHER, Ontonagon, MI

Built 1983 Load: 32.7 t ADT: 150

M-64

Good

Over: DREISS CREEK

2.7 MI SW OF US-45, Ontonagon, MI

Built 1945 Load: 33.4 t ADT: 2,117

OLD M-28

Good

Over: TEN MILE CREEK

7 MI W OF EWEN, Ontonagon, MI

Built 2011 Load: 33.7 t ADT: 50

M-28

Good

Over: BALTIMORE RIVER

1.5 MI W OF US-45, Ontonagon, MI

Built 1968 Load: 34.3 t ADT: 2,075

M-26

Good

Over: E BR FIRESTEEL RIVER

1.9 MI NE OF M-38, Ontonagon, MI

Built 2021 Load: 34.3 t ADT: 1,425

FIRESTEEL ROAD

Good

Over: FLINTSTEEL RIVER

4.5 MI E OF ONTONAGON, Ontonagon, MI

Built 1999 Load: 35.3 t ADT: 240

LAKE SHORE DRIVE

Good

Over: FLINTSTEEL RIVER

4 MI E OF ONTONAGON, Ontonagon, MI

Built 1980 Load: 35.5 t ADT: 200

MCRAE ROAD

Good

Over: S BR ONTONAGON RIVER

0.5 MI S OF EWEN, Ontonagon, MI

Built 1988 Load: 36.4 t ADT: 180

M-28

Good

Over: W BR ONTONAGON RIVER

2.3 MI E OF E JCT M-64, Ontonagon, MI

Built 1965 Load: 36.6 t ADT: 1,331

HOKENS ROAD

Good

Over: TEN MILE CREEK

6 MI WEST OF EWEN, Ontonagon, MI

Built 1988 Load: 37.3 t ADT: 150

M-64

Good

Over: DUCK CREEK

4.9 MI NE OF M-107, Ontonagon, MI

Built 1968 Load: 38.6 t ADT: 875

M-38

Good

Over: W BR OF FIRESTEEL RIVER

2.7 MI E OF M-26, Ontonagon, MI

Built 1958 Load: 43.1 t ADT: 754

BECK ROAD

Good

Over: FLINTSTEEL RIVER

5 MI E OF ONTONAGON, Ontonagon, MI

Built 1987 Load: 43.6 t ADT: 10

M-28

Good

Over: SO BR ONTONAGON RIVER

4.7 MI W OF US-45 (EWEN), Ontonagon, MI

Built 1990 Load: 43.7 t ADT: 2,398

GARDNER ROAD

Good

Over: MUD CREEK

6 MI S OF MASS, Ontonagon, MI

Built 1992 Load: 44.5 t ADT: 150

WILDERNESS DRIVE

Good

Over: FIRESTEEL RIVER

10 MI E OF ONTONOGON, Ontonagon, MI

Built 2009 Load: 45.0 t ADT: 50

KANGAS ROAD

Good

Over: W BR FIRESTEEL RIVER

5 MI N OF GREENLAND, Ontonagon, MI

Built 2009 Load: 45.0 t ADT: 50

M-26

Good

Over: W BR FIRESTEEL RIVER

1.3 MI NE OF M-38, Ontonagon, MI

Built 2021 Load: 45.4 t ADT: 1,425

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.