Total bridges
171
Public highway bridges in Sanilac County
County profile · official public datasets
Sanilac County, MI
171 public highway bridges tracked in the FHWA National Bridge Inventory: 31.6% rated Good, 58.5% Fair, 9.9% Poor.
- 171
- Public bridges
- 31.6%
- Good condition
- 9.9%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Sanilac County posts a better-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.
- Top 47%
- lowest Poor share in state
- 9.9%
- Poor-condition share
- 171
- public highway bridges
- 1978
- 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.
Sanilac County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Sanilac County ranks #39 of 83 Michigan counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 9.9%). Sanilac County, Michigan contains 171 public highway bridges. Roughly 31.6% are rated “Good,” 58.5% “Fair,” and 9.9% “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
31.6%
54 of 171 rated 7-9
Fair condition
58.5%
100 of 171 rated 5-6
Poor condition
9.9%
17 of 171 rated 4 or below
In-state Poor-share rank
#39 of 83
Among Michigan counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 171 NBI-tracked bridges by lowest applicable component rating.
Good 31.6% (54)
Fair 58.5% (100)
Poor 9.9% (17)
Sanilac County's Poor-condition bridges carry 20,523 vehicle crossings a day
That is 11.7% of the county's reported daily bridge traffic on 9.9% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 1,207 crossings a day against 1,529 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 171 of 171 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
30.4% of Sanilac County's bridges have passed the 50-year mark
52 of the 171 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 31.6% 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 26.6% of the county's Poor-condition bridge traffic
M-46 over BLACK RIVER, built 1947, carries 5,462 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 17-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 20,523 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Sanilac County's bridges were built
171 bridges with a recorded construction year, grouped by decade
- 1900s 2
1900–1909
2 bridges
- 1910s 1
1910–1919
1 bridges
- 1920s 3
1920–1929
3 bridges
- 1930s 15
1930–1939
15 bridges
- 1940s 5
1940–1949
5 bridges
- 1950s 9
1950–1959
9 bridges
- 1960s 7
1960–1969
7 bridges
- 1970s
1970–1979
21 bridges
- 1980s
1980–1989
52 bridges
- 1990s 19
1990–1999
19 bridges
- 2000s
2000–2009
28 bridges
- 2010s 6
2010–2019
6 bridges
- 2020s 3
2020–2029
3 bridges
What this shows Construction peaked in the 1980s, when 52 of the county's bridges still in the inventory were built, which is 30.4% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year (1978) matches the Michigan average (1976).
How Sanilac County compares with Michigan's closest counties by inventory size
The 5 Michigan counties nearest Sanilac County in number of bridges, with their condition splits. Its 9.9% Poor share is the 3rd-lowest of these 6. Its average build year of 1978 against a peer-group mean of 1977 is in line with the group.
Showing the 5 closest of 82 Michigan counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Sanilac County (this page) | 171 | 31.6% | 58.5% | 9.9% | 1978 |
| Gratiot County | 167 | 40.7% | 47.3% | 12% | 1975 |
| Bay County | 166 | 30.1% | 53% | 16.9% | 1974 |
| Livingston County | 165 | 26.7% | 58.8% | 14.5% | 1974 |
| Lapeer County | 163 | 36.2% | 54.6% | 9.2% | 1982 |
| Shiawassee County | 163 | 45.4% | 45.4% | 9.2% | 1981 |
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 Sanilac 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 Sanilac County, both outside Michigan so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside MI (171 bridges here).
- Crenshaw County, AL · 171 bridges
- Miami County, IN · 171 bridges
- Lincoln County, LA · 171 bridges
- Pine County, MN · 171 bridges
Similar average build year
Nearest mean year-built outside MI (1978 here).
- Orange County, CA · avg 1978 · 1,164 bridges
- Sumner County, KS · avg 1978 · 659 bridges
- Allen County, IN · avg 1978 · 613 bridges
- Livingston County, IL · avg 1978 · 579 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
All bridges (171)
BAD AXE ROAD
FairOver: TYRE I/C DRAIN EXTN
SEC 7 AUSTIN TWP, Sanilac, MI
Built 1988 Load: 11.3 t ADT: 150
FARGO ROAD
FairOver: BLACK CREEK
SEC 23-24 FREMONT TWP, Sanilac, MI
Built 2000 Load: 12.3 t ADT: 170
PALDI ROAD
FairOver: SPEAKER-MAPLE VALLEY DRN
SEC 21 ELK TWP, Sanilac, MI
Built 1969 Load: 13.9 t ADT: 200
STILSON ROAD
FairOver: SETTER DRAIN
SEC11 12 13&14 FLYNN TWP, Sanilac, MI
Built 1979 Load: 14.3 t ADT: 170
PATTERSON ROAD
FairOver: S FORK OF N BR CASS RIV
SEC 16-17 AUSTIN TWP, Sanilac, MI
Built 1985 Load: 14.9 t ADT: 150
FRENCH LINE ROAD
FairOver: BLACK RIVER I/C DRAIN
SEC 23-26 WASHINGTON TWP, Sanilac, MI
Built 1992 Load: 15.6 t ADT: 510
SHEPHARD ROAD
FairOver: SETTER I/C DRAIN
SEC 14-15 FLYNN TWP, Sanilac, MI
Built 1970 Load: 17.5 t ADT: 835
RICHARDS ROAD
FairOver: WHITE CREEK I/C DRAIN
SEC 28-33 LAMOTTE TWP, Sanilac, MI
Built 1973 Load: 19.1 t ADT: 150
SNOVER ROAD
FairOver: WHITE CREEK I/C DRAIN
SEC 17-20 LAMOTTE TWP, Sanilac, MI
Built 1983 Load: 20.1 t ADT: 875
LESLIE ROAD
FairOver: MIDDLE BR CASS RIVER
SEC 14-15 EVERGREEN TWP, Sanilac, MI
Built 1905 Load: 21.7 t ADT: 160
MUSHROOM ROAD
FairOver: WHITE CREEK I/C DRAIN
SEC 5-8 LAMOTTE TWP, Sanilac, MI
Built 1970 Load: 21.7 t ADT: 200
RANGE LINE ROAD
FairOver: BERRY DRAIN
SEC 19 BRIDGEHAMPTON TWP, Sanilac, MI
Built 1982 Load: 22.0 t ADT: 225
HARRINGTON ROAD
FairOver: SPEAKER-MAPLE VALLEY DRN
SEC 21-28 ELK TWP, Sanilac, MI
Built 1960 Load: 22.0 t ADT: 300
SETTER ROAD
FairOver: SETTER I/C DRAIN
SEC 14 FLYNN TWP, Sanilac, MI
Built 1980 Load: 24.3 t ADT: 120
M-25
FairOver: MILL CREEK
IN FORESTVILLE, Sanilac, MI
Built 1934 Load: 24.5 t ADT: 788
M-19
FairOver: MIDDLE BR CASS RIVER
7.8 MI N OF M-46, Sanilac, MI
Built 1952 Load: 24.6 t ADT: 1,718
M-19
FairOver: BR CASS RIVER
8.1 MI N OF M-46, Sanilac, MI
Built 1952 Load: 24.6 t ADT: 1,718
WHEELER ROAD
FairOver: S FORK OF N BR CASS RIV
SEC 17-18 AUSTIN TWP, Sanilac, MI
Built 1950 Load: 24.6 t ADT: 300
SCHOOL ROAD
FairOver: SPEAKER-MAPLE VALLEY DRN
SEC 8 SPEAKER TWP, Sanilac, MI
Built 1970 Load: 24.6 t ADT: 225
FRENCH LINE ROAD
FairOver: BEALS & FRIZZLE DRAIN
SEC 21-28 WATERTOWN TWP, Sanilac, MI
Built 1930 Load: 26.2 t ADT: 610
DOWNINGTON ROAD
FairOver: MIDDLE BR DRAIN
SEC 35 ARGYLE TWP, Sanilac, MI
Built 1969 Load: 27.5 t ADT: 180
MOWERSON ROAD
FairOver: MCDONALD DRAIN
SEC 7 ELK TWP, Sanilac, MI
Built 1988 Load: 28.5 t ADT: 90
WALKER ROAD
FairOver: S BR CASS RIVER I/C DRN
SEC 18-19 ELMER TWP, Sanilac, MI
Built 1981 Load: 28.8 t ADT: 225
APPLEGATE ROAD
FairOver: BEALS & FRIZZLE DRAIN
SEC 28-33 WATERTOWN TWP, Sanilac, MI
Built 2001 Load: 31.1 t ADT: 155
MELVIN ROAD
FairOver: ELK CREEK DRAIN
SEC 29-30 ELK TWP, Sanilac, MI
Built 1930 Load: 31.4 t ADT: 565
BURNS LINE ROAD
FairOver: MILL CREEK
SEC 11-14 WORTH TWP, Sanilac, MI
Built 1950 Load: 31.4 t ADT: 300
DECKERVILLE ROAD
FairOver: S BR CASS RIVER I/C DRN
SEC 27-34 EVERGREEN TWP, Sanilac, MI
Built 1930 Load: 31.8 t ADT: 1,023
GERMANIA ROAD
FairOver: DUFF DRAIN
SEC 23-24 MARLETTE TWP, Sanilac, MI
Built 2001 Load: 32.7 t ADT: 966
FREIBERGER ROAD
FairOver: MIDDLE BR DRAIN
SEC 26-27 ARGYLE TWP, Sanilac, MI
Built 1970 Load: 33.0 t ADT: 200
WASHINGTON ROAD
FairOver: ELK CREEK DRAIN
SEC 9-16 WASHINGTON TWP, Sanilac, MI
Built 1983 Load: 34.0 t ADT: 225
M-25
FairOver: INDIAN CREEK
11.0 MI N OF M-46, Sanilac, MI
Built 1949 Load: 34.7 t ADT: 1,173
RUTH ROAD
FairOver: BLACK RIVER I/C DRAIN
SEC 29-30 BRIDGEHAMPTON, Sanilac, MI
Built 1952 Load: 35.0 t ADT: 3,325
CRIBBINS ROAD
FairOver: BLACK CREEK DRAIN
SEC 18 WORTH TWP, Sanilac, MI
Built 1987 Load: 35.2 t ADT: 210
M-53
FairOver: S BR CASS RIVER
9.5 MI N OF M-46, Sanilac, MI
Built 1977 Load: 35.3 t ADT: 3,600
TODD ROAD
FairOver: BLACK CREEK DRAIN
SEC 22-23 FREMONT TWP, Sanilac, MI
Built 2007 Load: 35.5 t ADT: 1,170
DECKER ROAD
FairOver: S BR CASS RIVER I/C DRN
SEC 15-16 EVERGREEN TWP, Sanilac, MI
Built 1969 Load: 36.5 t ADT: 135
FRENCH LINE ROAD
FairOver: SMALLDON DRAIN
SEC 22-27 WATERTOWN TWP, Sanilac, MI
Built 1930 Load: 37.1 t ADT: 610
APPLEGATE ROAD
FairOver: BLACK RIVER
SEC 26-35 WASHINGTON TWP, Sanilac, MI
Built 1979 Load: 37.3 t ADT: 2,025
PALDI ROAD
FairOver: ELK CREEK DRAIN
SEC 16 ELK TWP, Sanilac, MI
Built 1950 Load: 37.3 t ADT: 165
M-53
FairOver: N BR CASS RIVER
2.5 MI S OF HURON CO LINE, Sanilac, MI
Built 1985 Load: 37.6 t ADT: 4,062
CASH ROAD
FairOver: ELK CREEK DRAIN
SEC 34-35 WATERTOWN TWP, Sanilac, MI
Built 2004 Load: 37.8 t ADT: 300
HOADLEY ROAD
FairOver: N BR CASS RIVER
SEC16-17 GREENLEAF TWP, Sanilac, MI
Built 1991 Load: 38.8 t ADT: 240
M-46
FairOver: N BRANCH WHITE CREEK
2.2 MI E OF TUSCOLA COL, Sanilac, MI
Built 1932 Load: 38.9 t ADT: 3,484
SNOVER ROAD
FairOver: S BR CASS RIVER I/C DRN
SEC 18-19 MOORE TWP, Sanilac, MI
Built 1983 Load: 39.2 t ADT: 967
HURON LINE ROAD
FairOver: TYRE I/C DRAIN EXT
AUSTIN TWP SEC 5 & 6, Sanilac, MI
Built 1974 Load: 39.9 t ADT: 40
M-25
FairOver: SHERMAN CREEK
4.1 MI N OF M-46, Sanilac, MI
Built 1939 Load: 40.5 t ADT: 2,969
GERMANIA ROAD
FairOver: S FORK OF N BR CASS RIV
SEC 13-14 GREENLEAF TWP, Sanilac, MI
Built 1976 Load: 40.8 t ADT: 522
SHEPHARD ROAD
FairOver: ELK CREEK DRAIN
SEC 10-11 MAPLE VALLEYTWP, Sanilac, MI
Built 1960 Load: 41.1 t ADT: 1,600
DOWNINGTON ROAD
FairOver: CHERRY CREEK
SEC 33 FORESTER TWP, Sanilac, MI
Built 1995 Load: 41.1 t ADT: 160
M-19
FairOver: ELK CREEK
6.6 MI S OF M-46, Sanilac, MI
Built 2000 Load: 41.5 t ADT: 4,553
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.