Total bridges
297
Public highway bridges in Monroe County
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.
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
- pre-1900 1
Built before 1900
1 bridges
- 1900s 1
1900–1909
1 bridges
- 1910s 1
1910–1919
1 bridges
- 1920s 16
1920–1929
16 bridges
- 1930s 13
1930–1939
13 bridges
- 1940s 6
1940–1949
6 bridges
- 1950s
1950–1959
55 bridges
- 1960s
1960–1969
37 bridges
- 1970s
1970–1979
49 bridges
- 1980s
1980–1989
30 bridges
- 1990s 21
1990–1999
21 bridges
- 2000s
2000–2009
35 bridges
- 2010s 19
2010–2019
19 bridges
- 2020s 13
2020–2029
13 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).
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.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| St. Clair County | 327 | 41.3% | 50.5% | 8.3% | 1985 |
| Saginaw County | 315 | 28.9% | 52.7% | 18.4% | 1979 |
| Monroe County (this page) | 297 | 30% | 54.5% | 15.5% | 1974 |
| Berrien County | 272 | 27.6% | 66.5% | 5.9% | 1979 |
| Washtenaw County | 262 | 23.3% | 56.5% | 20.2% | 1975 |
| Ottawa County | 254 | 40.9% | 52.8% | 6.3% | 1977 |
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).
- Crawford County, KS · 297 bridges
- Kingfisher County, OK · 297 bridges
- Sarasota County, FL · 298 bridges
- Rutherford County, NC · 298 bridges
Similar average build year
Nearest mean year-built outside MI (1974 here).
- Knox County, TN · avg 1974 · 588 bridges
- Summit County, OH · avg 1974 · 563 bridges
- Onondaga County, NY · avg 1974 · 472 bridges
- Orange County, NY · avg 1974 · 472 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Fair-condition bridges (162)
SMITH ROAD
FairOver: HALFWAY CREEK
.02 MI E OF DOUGLAS ROAD, Monroe, MI
Built 1960 Load: 34.3 t ADT: 8,220
PETERSBURG ROAD
FairOver: LITTLE RAISIN RIVER
1.75 MI S OF M-50, Monroe, MI
Built 1978 Load: 34.7 t ADT: 689
US-23 SB
FairOver: TEN MILE CREEK
0.5 MI N OHIO STATE LINE, Monroe, MI
Built 1959 Load: 35.0 t ADT: 19,270
DUNBAR RD
FairOver: I-75
2.8 MI SW OF M-50, Monroe, MI
Built 1955 Load: 35.0 t ADT: 400
EXETER RD
FairOver: STONY CREEK
.10 MI NO OF STONY CR RD, Monroe, MI
Built 1973 Load: 35.0 t ADT: 2,080
US-23 NB
FairOver: TEN MILE CREEK
0.5 MI N OHIO STATE LINE, Monroe, MI
Built 1959 Load: 35.3 t ADT: 19,270
COUSINO RD
FairOver: MUDDY CREEK
1.3 MI N OF VICTORY RD, Monroe, MI
Built 1927 Load: 35.3 t ADT: 380
HURD RD
FairOver: I-75
1.4 MI NE OF M-50, Monroe, MI
Built 1956 Load: 35.6 t ADT: 1,970
US-23 NB
FairOver: BEAR CREEK
3.5 MI N OF M-50, Monroe, MI
Built 1961 Load: 36.0 t ADT: 16,735
US-23 NB
FairOver: N BR MACON RIVER
4.7 MI N OF M-50, Monroe, MI
Built 1961 Load: 36.0 t ADT: 16,735
I-75
FairOver: PAPER CO WATER MAINS
IN MONROE, Monroe, MI
Built 1955 Load: 36.0 t ADT: 63,962
US-24
FairOver: HURON RIVER
@ WAYNE CO LINE, Monroe, MI
Built 2001 Load: 36.3 t ADT: 24,306
OELKE ROAD
FairOver: SALINE RIVER
0.1 MI W OF TOWNSEND ROAD, Monroe, MI
Built 1990 Load: 36.6 t ADT: 78
BRANDON RD
FairOver: SWAN CREEK
.05 MI N OF SWAN CRK RD, Monroe, MI
Built 1965 Load: 36.9 t ADT: 2,210
US-23 SB
FairOver: BEAR CREEK
3.8 MI N OF M-50, Monroe, MI
Built 1961 Load: 37.3 t ADT: 16,735
M-125
FairOver: RAISIN RIVER
IN MONROE, Monroe, MI
Built 1927 Load: 37.3 t ADT: 21,209
CARLETON-ROCKWOOD
FairOver: I-275
5 MI W OF ROCKWOOD, Monroe, MI
Built 1973 Load: 37.3 t ADT: 1,870
COLLINS ROAD
FairOver: NORTH MACON DRAIN
0.7 MI E OF DENNISON ROAD, Monroe, MI
Built 1897 Load: 37.3 t ADT: 21
YAX ROAD
FairOver: SANDY CREEK
.2 MI N OF SANDY CREEK RD, Monroe, MI
Built 1982 Load: 37.3 t ADT: 390
US-23
FairOver: M-50
IN DUNDEE, Monroe, MI
Built 1958 Load: 37.6 t ADT: 34,524
CONE RD
FairOver: US-23
5.2 MI N OF M-50, Monroe, MI
Built 1961 Load: 38.2 t ADT: 2,250
BLUE BUSH ROAD
FairOver: LITTLE SANDY CREEK
0.12 MI E OF RAISINVILLE, Monroe, MI
Built 1980 Load: 38.9 t ADT: 5,160
ALBAIN ROAD
FairOver: LAPLAISANCE CREEK
0.1 MI NE OF HULL ROAD, Monroe, MI
Built 1955 Load: 39.1 t ADT: 2,410
REA ROAD
FairOver: NORTH MACON DRAIN
0.3 MI N OF COLLINS ROAD, Monroe, MI
Built 1993 Load: 39.1 t ADT: 67
US-24
FairOver: SWAN CREEK
4.0 MI SW OF WAYNE COL, Monroe, MI
Built 1922 Load: 39.2 t ADT: 10,923
M-125
FairOver: OTTER CREEK
4.7 MI SW OF M-50, Monroe, MI
Built 1964 Load: 39.2 t ADT: 8,305
IDA MAYBEE RD
FairOver: MILL RACE
4.25 MI N OF IDA WEST RD, Monroe, MI
Built 1958 Load: 39.2 t ADT: 2,666
I-75
FairOver: NORFOLK SOUTHERN RR
0.9 MI N OF M-50, Monroe, MI
Built 1955 Load: 39.5 t ADT: 65,200
COLF ROAD
FairOver: SWAN CREEK
0.65 MI E OF SUMPTER RD, Monroe, MI
Built 1995 Load: 39.5 t ADT: 160
COLF ROAD
FairOver: SWAN CREEK
1 MI W OF CARLETON WEST, Monroe, MI
Built 1995 Load: 39.5 t ADT: 240
US-23 NB
FairOver: N BR TEN MILE CREEK
2.0 MI N OHIO STATE LINE, Monroe, MI
Built 1959 Load: 39.9 t ADT: 18,124
US-23 SB
FairOver: N BR TEN MILE CREEK
2.0 MI N OHIO STATE LINE, Monroe, MI
Built 1959 Load: 39.9 t ADT: 18,124
US-24
FairOver: CSX RR
1.5 MI SW OF M-125, Monroe, MI
Built 1925 Load: 40.2 t ADT: 18,282
I-75 &M-125 CONN
FairOver: I-75
1.6 MI N OF STATE LINE, Monroe, MI
Built 1975 Load: 40.2 t ADT: 2,700
NEWBURG ROAD
FairOver: N BRANCH SWAN CREEK
0.6 MI E OF GRAFTON ROAD, Monroe, MI
Built 1999 Load: 40.5 t ADT: 400
DOUGLAS ROAD
FairOver: LOCKWOOD DRAIN
0.3 MI N OF MOROCCO ROAD, Monroe, MI
Built 1960 Load: 40.8 t ADT: 230
PETERSBURG ROAD
FairOver: MILAN CENTER DRAIN
.39 MI N OF CONE ROAD, Monroe, MI
Built 1980 Load: 40.9 t ADT: 80
POST RD
FairOver: I-75
2.0 MI SW OF NEWPORT, Monroe, MI
Built 1975 Load: 41.1 t ADT: 270
TIMBERS ROAD
FairOver: STONY CREEK
.1 MI N OF S STONY CR RD, Monroe, MI
Built 1978 Load: 41.1 t ADT: 180
ANN ARBOR ROAD
FairOver: BEAR SWAMP CREEK
3.95 MI N OF M 50, Monroe, MI
Built 1947 Load: 41.8 t ADT: 2,766
SUMPTERROAD
FairOver: STONY CREEK
.25 MI N OF S.STONY CR RD, Monroe, MI
Built 1966 Load: 41.8 t ADT: 1,820
MARTINSVILLE ROAD
FairOver: SWAN CREEK
0.1 MI SOUTH OF COLF RD, Monroe, MI
Built 1976 Load: 42.1 t ADT: 129
HACK ROAD
FairOver: NORTH MACON CREEK
0.6 MI E OF WESTFALL ROAD, Monroe, MI
Built 1983 Load: 42.4 t ADT: 87
RAISINVILLE ROAD
FairOver: WILLOW RUN DRAIN
.3 MI. N. OF N. CUSTER RD, Monroe, MI
Built 1963 Load: 42.6 t ADT: 2,490
PLATT ROAD
FairOver: BEAR SWAMP CREEK
0.7 MI S OF CONE ROAD, Monroe, MI
Built 1950 Load: 43.1 t ADT: 214
M-50
FairOver: S BR MACON RIVER
2.5 MI W OF DUNDEE, Monroe, MI
Built 1953 Load: 43.4 t ADT: 6,646
I-75 NB
FairOver: LAPLAISANCE CREEK
4.2 MI SW OF M-50, Monroe, MI
Built 1954 Load: 43.4 t ADT: 30,558
NEWPORT RD
FairOver: I-275
SE OF CARLETON, Monroe, MI
Built 1973 Load: 43.4 t ADT: 460
COUPER ROAD
FairOver: BEAR SWAMP CREEK
0.7 MI E OF PLATT ROAD, Monroe, MI
Built 1950 Load: 43.4 t ADT: 20
SECTION ROAD
FairOver: OTTAWA LAKE OUTLET
0.13 MI E OF JEFFS ROAD, Monroe, MI
Built 1992 Load: 43.7 t ADT: 532
Read our methodology - how this data is sourced, computed, and verified.
Related
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.