County profile · official public datasets

Monroe County, MI

297 public highway bridges tracked in the FHWA National Bridge Inventory: 30% rated Good, 54.5% Fair, 15.5% Poor.

297
Public bridges
30%
Good condition
15.5%
Poor condition

The verdict

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

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

59th
of 83 on Poor share
15.5%
Poor-condition share
297
public highway bridges
1974
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.

Monroe County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Monroe County ranks #59 of 83 Michigan counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 15.5%). Monroe County, Michigan contains 297 public highway bridges. Roughly 30% are rated “Good,” 54.5% “Fair,” and 15.5% “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

297

Public highway bridges in Monroe County

Good condition

30%

89 of 297 rated 7-9

Fair condition

54.5%

162 of 297 rated 5-6

Poor condition

15.5%

46 of 297 rated 4 or below

In-state Poor-share rank

#59 of 83

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

Condition distribution

Share of 297 NBI-tracked bridges by lowest applicable component rating.

Good
30% (89)
Fair
54.5% (162)
Poor
15.5% (46)

Monroe County's Poor-condition bridges carry 203,824 vehicle crossings a day

That is 7.9% of the county's reported daily bridge traffic on 15.5% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 4,431 crossings a day against 9,265 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 297 of 297 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

53.5% of Monroe County's bridges have passed the 50-year mark

159 of the 297 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 30% 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 33.3% of the county's Poor-condition bridge traffic

I-75 over CONRAIL RAISIN R FRONT, built 1955, carries 67,800 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 46-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 203,824 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Monroe County's bridges were built

297 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1950s, when 55 of the county's bridges still in the inventory were built, which is 18.5% of those with a recorded year. That cohort is now 65 to 74 years old in the 2024 inventory. Its average build year (1974) matches the Michigan average (1976).

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

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

The 5 Michigan counties nearest Monroe County in number of bridges, with their condition splits. Its 15.5% Poor share is the 4th-lowest of these 6. Its average build year of 1974 against a peer-group mean of 1979 is 5 years older.

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

Bridge inventory size and condition shares for Monroe County and the 5 Michigan counties closest to it in inventory size
County Bridges Poor
St. Clair County 327 8.3%
Saginaw County 315 18.4%
Monroe County (this page) 297 15.5%
Berrien County 272 5.9%
Washtenaw County 262 20.2%
Ottawa County 254 6.3%

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

Similar inventory size

Nearest county inventories outside MI (297 bridges here).

Similar average build year

Nearest mean year-built outside MI (1974 here).

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

All 297 Good 89 Fair 162 Poor 46

All bridges (297)

S HURON R DR

Good

Over: I-75

IN S ROCKWOOD, Monroe, MI

Built 2008 Load: 40.5 t ADT: 7,300

US-24

Good

Over: LITTLE SWAN CREEK

4.2 MI SW OF WAYNE COL, Monroe, MI

Built 1922 Load: 40.8 t ADT: 10,923

I-75 NB

Good

Over: STONY CREEK

3.2 MI NE OF M-50, Monroe, MI

Built 2015 Load: 40.8 t ADT: 36,850

IDA CENTER ROAD

Good

Over: LOCKWOOD DRAIN

0.85 E OF LEWIS ROAD, Monroe, MI

Built 2021 Load: 40.8 t ADT: 920

TURK ROAD

Good

Over: OTTAWA LAKE OUTLET

1.2 MI N OF STERNS ROAD, Monroe, MI

Built 2005 Load: 41.1 t ADT: 120

HEAD-O-LAKE RD

Good

Over: OTTAWA LAKE OUTLET

1.6 MI NO OF OLD US 223, Monroe, MI

Built 2002 Load: 42.1 t ADT: 570

SECOR RD

Good

Over: LOCKWOOD DRAIN

2.4 MI N OF CO RD 151, Monroe, MI

Built 2013 Load: 42.1 t ADT: 1,340

I-75 NB

Good

Over: HALFWAY CREEK

0.3 MI N OHIO STATE LINE, Monroe, MI

Built 2019 Load: 42.4 t ADT: 27,900

I-75 SB

Good

Over: HALFWAY CREEK

0.3 MI N OHIO STATE LINE, Monroe, MI

Built 2020 Load: 42.4 t ADT: 27,900

READY ROAD

Good

Over: SWAN CREEK

0.1 MI W OF CREEK ROAD, Monroe, MI

Built 2015 Load: 42.4 t ADT: 1,110

I-75 SB

Good

Over: BAY CREEK

4.2 MI NE OHIO STATE LINE, Monroe, MI

Built 2020 Load: 42.8 t ADT: 27,575

NADEAU RD

Good

Over: I-75

2.8 MI NE OF M-50, Monroe, MI

Built 2022 Load: 42.8 t ADT: 19,950

I-75 NB

Good

Over: BAY CREEK

4.2 MI NE OHIO STATE LINE, Monroe, MI

Built 2019 Load: 43.1 t ADT: 27,575

DENNISON ROAD

Good

Over: SWAMP RAISIN CREEK

0.4 MI S OF BREWER ROAD, Monroe, MI

Built 2005 Load: 43.1 t ADT: 80

STERNS RD

Good

Over: OTTAWA LAKE OUTLET

2.45 MI E OF OLD US 223, Monroe, MI

Built 1997 Load: 44.1 t ADT: 10,500

I-75 SB

Good

Over: STONY CREEK

3.2 MI NE OF M-50, Monroe, MI

Built 2016 Load: 44.7 t ADT: 36,850

I-75 SB

Good

Over: SANDY CREEK

1.2 MI NE OF M-50, Monroe, MI

Built 2016 Load: 45.0 t ADT: 25,200

STERNS RD

Good

Over: I-75

1.2 MI N OHIO STATE LINE, Monroe, MI

Built 2009 Load: 46.0 t ADT: 1,360

ANN ARBOR ROAD

Good

Over: NORTH MACON CREEK

0.2 MI N OF OSTRANDER RD, Monroe, MI

Built 1947 Load: 46.0 t ADT: 2,378

DREW STREET

Good

Over: SWAN CREEK

0.15 MI N OF SWAN CREEK R, Monroe, MI

Built 2015 Load: 47.3 t ADT: 770

NORTH DIXIE HWY

Good

Over: LITTLE SWAN CREEK

0.6 MI S OF SWAN CREEK RD, Monroe, MI

Built 2002 Load: 47.3 t ADT: 5,090

I-75 NB

Good

Over: BAY CREEK RD

3.6 MI NE OHIO STATE LINE, Monroe, MI

Built 2019 Load: 47.6 t ADT: 27,575

I-75 SB

Good

Over: BAY CREEK RD

3.6 MI NE OHIO STATE LINE, Monroe, MI

Built 2020 Load: 48.0 t ADT: 27,575

NORTH DIXIE HWY

Good

Over: STONY CREEK

3.0 MI NE OF I-75, Monroe, MI

Built 1966 Load: 48.0 t ADT: 9,388

HICKORY CREEK DR

Good

Over: INDIAN CREEK

0.5 MI E OF LEWIS AVE, Monroe, MI

Built 2004 Load: 48.0 t ADT: 250

LAPLAISANCE ROAD

Good

Over: WOODCHUCK CREEK

4.2 MI E OF US 25, Monroe, MI

Built 2003 Load: 49.9 t ADT: 350

DENNISON RD

Good

Over: MIDDLE BRANCH MACON DRAI

.3 MI NO OF M 50, Monroe, MI

Built 2017 Load: 49.9 t ADT: 484

SUDER ROAD

Good

Over: HOOPER RUN DRAIN

0.1 M S OF STERNS ROAD, Monroe, MI

Built 2006 Load: 50.2 t ADT: 1,329

US-24

Good

Over: LITTLE LAKE CREEK

4.3 MI N OHIO STATE LINE, Monroe, MI

Built 2018 Load: 51.2 t ADT: 7,265

I-75

Good

Over: NS & CN RAILROAD

0.7 MI N OF M-50, Monroe, MI

Built 1956 Load: 54.4 t ADT: 65,200

I-275 SB

Good

Over: I-75

5 MI N OF MONROE, Monroe, MI

Built 1973 Load: 55.4 t ADT: 1,210

SUMMIT STREET

Good

Over: HALFWAY CREEK

0.4 MI N OF STATE LINE, Monroe, MI

Built 1991 Load: 55.7 t ADT: 1,912

I-75 NB

Good

Over: HURON RIVER

IN S ROCKWOOD, Monroe, MI

Built 2009 Load: 56.1 t ADT: 26,929

BREWER RD

Good

Over: SWAMP RAISIN CREEK

2.75 MI E OF COUNTY LINE, Monroe, MI

Built 2009 Load: 56.8 t ADT: 260

WILCOX ROAD

Good

Over: MID. BRANCH MACON DRAIN

0.2 MI N OF KENT ROAD, Monroe, MI

Built 1976 Load: 57.7 t ADT: 210

WILCOX ROAD

Good

Over: SOUTH BRANCH MACON RIVER

1.1 MI N OF M 50, Monroe, MI

Built 2008 Load: 59.6 t ADT: 460

I-75 SB

Good

Over: HURON RIVER

IN S ROCKWOOD, Monroe, MI

Built 2009 Load: 59.6 t ADT: 31,814

RAISINVILLE RD

Good

Over: PLUM CREEK

1.25 MI S OF M 50, Monroe, MI

Built 2007 Load: 63.2 t ADT: 3,060

WABASH RD

Good

Over: NORTH MACON CREEK

.65 MI NO OF CONE RD, Monroe, MI

Built 1948 Load: 63.5 t ADT: 1,330

LAVOY ROAD

Good

Over: INDIAN CREEK

0.1 MI E OF US 24, Monroe, MI

Built 2012 Load: 63.8 t ADT: 2,150

US TURNPIKE

Good

Over: MOUILLEE CREEK

1.25 MI SW OF COUNTY LINE, Monroe, MI

Built 2006 Load: 64.8 t ADT: 1,768

I-75

Good

Over: LITTLE LAKE CREEK

540 FT N OF RAMP B, Monroe, MI

Built 2020 Load: 65.1 t ADT: 58,900

DENNISON RD

Good

Over: N DR MID BR MACON R

1.25 MI N OF M 50, Monroe, MI

Built 2011 Load: 70.6 t ADT: 430

PETERSBURG RD

Good

Over: RIVER RAISIN

0.3 MI N OF IDA WEST RD, Monroe, MI

Built 1959 Load: 74.0 t ADT: 920

FINZEL ROAD

Good

Over: STONY CREEK OVERFLOW

0.1 MI N OF S STONY CR RD, Monroe, MI

Built 2009 Load: 74.2 t ADT: 170

I-275

Good

Over: LITTLE SWAN CREEK

0.35 MI N OF E SIGLER RD, Monroe, MI

Built 1968 Load: 75.5 t ADT: 27,104

OAKVILLE WALTZ RD

Good

Over: STONY CREEK

6.7 MI E OF US 23, Monroe, MI

Built 2003 Load: 77.1 t ADT: 2,124

PETERSBURG ROAD

Good

Over: BEAR SWAMP CREEK

0.5 MI N OF COUPER ROAD, Monroe, MI

Built 2007 Load: 78.4 t ADT: 50

CARLETON ROCKWOOD

Good

Over: SWAN CREEK

1.3 MI E OF GRAFTON RD, Monroe, MI

Built 1964 Load: 79.7 t ADT: 3,630

EASTWOOD ROAD

Good

Over: PLUM CREEK

0.1 MI N OF DUNBAR ROAD, Monroe, MI

Built 2017 Load: 97.2 t ADT: 930

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.