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.
Good-condition bridges (54)
HALL ROAD
GoodOver: POTTS DRAIN
SEC 17-20 BUEL TWP, Sanilac, MI
Built 1980 Load: 17.2 t ADT: 135
HOADLEY ROAD
GoodOver: WHITE CREEK I /C DRAIN
SEC 16-17 LAMOTTE TWP, Sanilac, MI
Built 1978 Load: 17.8 t ADT: 165
ADAMS ROAD
GoodOver: WHITE CREEK I/C DRAIN
SEC 21-28 LAMOTTE TWP, Sanilac, MI
Built 1980 Load: 20.1 t ADT: 135
MORIARTEY ROAD
GoodOver: WHITE CREEK I/C DRAIN
SEC 9-16 LAMOTTE TWP, Sanilac, MI
Built 1980 Load: 22.0 t ADT: 150
CARROLL ROAD
GoodOver: ELK CREEK DRAIN
SEC 17-20 ELK TWP, Sanilac, MI
Built 1991 Load: 25.1 t ADT: 165
ARNOLD ROAD
GoodOver: MIDDLE BR CASS RIVER
SEC 13-18 ARGYLE TWP, Sanilac, MI
Built 1907 Load: 25.6 t ADT: 150
M-19
GoodOver: BR CASS RIVER
6.7 MI N OF M-46, Sanilac, MI
Built 2007 Load: 26.6 t ADT: 1,718
FRENCH LINE ROAD
GoodOver: DUFF DRAIN
SEC 22-27 MARLETTE TWP, Sanilac, MI
Built 2001 Load: 28.8 t ADT: 375
FRENCH LINE ROAD
GoodOver: S BR CASS RIVER I/C DRN
SEC 19-30 ELMER TWP, Sanilac, MI
Built 1986 Load: 29.8 t ADT: 314
HARRINGTON ROAD
GoodOver: ELK CREEK DRAIN
SEC 20-29 ELK TWP, Sanilac, MI
Built 1991 Load: 29.8 t ADT: 300
WOOD ROAD
GoodOver: DUFF DRAIN
SEC 22-23 MARLETTE TWP, Sanilac, MI
Built 2001 Load: 30.5 t ADT: 130
FRENCH LINE ROAD
GoodOver: DUFF DRAIN
SEC. 23-26 MARLETTE TWP., Sanilac, MI
Built 2001 Load: 31.8 t ADT: 435
HOADLEY ROAD
GoodOver: WHITE CREEK I/C DRAIN
SEC 8-9 LAMOTTE TWP, Sanilac, MI
Built 1986 Load: 32.4 t ADT: 165
M-90
GoodOver: W BR MILLS CREEK
6.8 MI E OF M-19, Sanilac, MI
Built 2006 Load: 32.7 t ADT: 5,001
FETTING ROAD
GoodOver: ELK CREEK DRAIN
SEC 35-36 WATERTOWN TWP, Sanilac, MI
Built 1983 Load: 32.7 t ADT: 302
GALBRAITH LINE RD
GoodOver: BIRCH CREEK
SEC 22-27 WORTH TWP, Sanilac, MI
Built 2003 Load: 33.4 t ADT: 2,020
FRENCH LINE ROAD
GoodOver: DUFF DRAIN
SEC 23-26 MARLETTE TWP, Sanilac, MI
Built 2001 Load: 33.7 t ADT: 435
M-19
GoodOver: HALE CREEK
WATERTOWN TWP SEC 28 & 29, Sanilac, MI
Built 2002 Load: 36.0 t ADT: 4,553
WILDCAT ROAD
GoodOver: BR OF BIRCH CREEK
SEC 27-28 WORTH TWP, Sanilac, MI
Built 2000 Load: 36.0 t ADT: 2,060
STILSON ROAD
GoodOver: ELK CREEK DRAIN
SEC 9-16 ELK TWP, Sanilac, MI
Built 1978 Load: 37.6 t ADT: 371
COOPER ROAD
GoodOver: S BR CASS RIVER I/C DRN
SEC 7-18 ELMER TWP, Sanilac, MI
Built 2005 Load: 37.6 t ADT: 240
M-90
GoodOver: BLACK RIVER
4.7 MI W US-25 IN CROSWEL, Sanilac, MI
Built 2023 Load: 38.9 t ADT: 8,400
AITKEN ROAD
GoodOver: BLACK RIVER I/C DRAIN
SEC 6-7 LEXINGTON TWP, Sanilac, MI
Built 2005 Load: 39.1 t ADT: 305
FISHER ROAD
GoodOver: JACKSON CREEK I/C DRAIN
SEC 31 FREMONT TWP, Sanilac, MI
Built 2016 Load: 39.5 t ADT: 200
M-90
GoodOver: E BR MILLS CREEK
7.5 MI E OF M-19, Sanilac, MI
Built 2000 Load: 40.8 t ADT: 5,001
AITKEN ROAD
GoodOver: ELK CREEK DRAIN
SEC 3-10 ELK TWP, Sanilac, MI
Built 1985 Load: 40.8 t ADT: 165
MUSHROOM ROAD
GoodOver: S BR CASS RIVER I/C DRN
SEC 1-12 LAMOTTE TWP, Sanilac, MI
Built 2001 Load: 40.8 t ADT: 155
MARLETTE ROAD
GoodOver: ELK CREEK DRAIN
SEC 33 WATERTOWN TWP, Sanilac, MI
Built 1983 Load: 41.8 t ADT: 725
M-90
GoodOver: SPRING CREEK
0.7 MI E OF M-19, Sanilac, MI
Built 2000 Load: 42.1 t ADT: 5,001
BANNER ROAD
GoodOver: ELK CREEK DRAIN
SEC 33-34 WATERTOWN TWP, Sanilac, MI
Built 1983 Load: 42.1 t ADT: 222
M-46
GoodOver: S BR CASS RIVER
2.0 MI W OF M-19, Sanilac, MI
Built 2007 Load: 43.1 t ADT: 3,484
M-19
GoodOver: BR OF ELK CREEK
6.5 MI S OF M-46, Sanilac, MI
Built 2000 Load: 44.1 t ADT: 4,553
LAMTON ROAD
GoodOver: GREENMAN I/C DRAIN
SEC 6 EVERGREEN TWP, Sanilac, MI
Built 2004 Load: 44.1 t ADT: 185
M-53
GoodOver: WHITE CREEK
5.8 MI N OF M-46, Sanilac, MI
Built 2006 Load: 45.4 t ADT: 4,415
SHABBONA ROAD
GoodOver: BLACK RIVER I/C DRAIN
SEC 23 26 WHEATLAND TWP, Sanilac, MI
Built 1986 Load: 46.0 t ADT: 225
FORESTER ROAD
GoodOver: BLACK RIVER I/C DRAIN
SEC 12-13 CUSTER TWP, Sanilac, MI
Built 1979 Load: 48.0 t ADT: 380
STONE ROAD
GoodOver: BLACK RIVER I/C DRAIN
SEC 14-23 WHEATLAND TWP, Sanilac, MI
Built 1991 Load: 48.6 t ADT: 225
APPLEGATE ROAD
GoodOver: ELK CREEK DRAIN
SEC 30-31 WASHINGTON TWP, Sanilac, MI
Built 1983 Load: 49.2 t ADT: 222
DECKERVILLE ROAD
GoodOver: BLACK RIVER I/C DRAIN
SEC 25-36 WHEATLAND TWP, Sanilac, MI
Built 1985 Load: 49.3 t ADT: 4,630
SHABBONA ROAD
GoodOver: MIDDLE BR DRAIN
SEC 21-28 ARGYLE TWP, Sanilac, MI
Built 1993 Load: 49.9 t ADT: 180
MILLS ROAD
GoodOver: BLACK RIVER & SMERCZ DRN
SEC 3-10 WHEATLAND TWP, Sanilac, MI
Built 2017 Load: 52.5 t ADT: 246
M-25
GoodOver: MILL CREEK
3.5 MI S OF M-90, Sanilac, MI
Built 2016 Load: 52.8 t ADT: 7,775
NICOL ROAD
GoodOver: BLACK RIVER I/C DRAIN
SEC 1-12 CUSTER TWP, Sanilac, MI
Built 2005 Load: 52.9 t ADT: 170
MILLER ROAD
GoodOver: S BR CASS RIVER I/C DRN
SEC 5-8 ELMER TWP, Sanilac, MI
Built 1986 Load: 56.1 t ADT: 225
BABCOCK ROAD
GoodOver: BIRCH CREEK
SEC 35-36 WORTH TWP, Sanilac, MI
Built 2015 Load: 58.3 t ADT: 259
M-90
GoodOver: MILLS CREEK
5.0 MI W OF US-25, Sanilac, MI
Built 2023 Load: 59.0 t ADT: 8,400
FRENCH LINE ROAD
GoodOver: ELK CREEK DRAIN
SEC 19-30 WASHINGTON TWP, Sanilac, MI
Built 1988 Load: 59.9 t ADT: 958
M-90
GoodOver: POTTS DRAIN
2.2 MI E OF M-19, Sanilac, MI
Built 1961 Load: 68.7 t ADT: 2,600
GERMANIA ROAD
GoodOver: EVERGREEN-AUSTIN DRAIN
SEC 13-14 EVERGREEN TWP, Sanilac, MI
Built 1986 Load: 76.1 t ADT: 514
MELVIN RD
GoodOver: MC DONALD DRAIN
150 N OF STILSON RD, Sanilac, MI
Built 2018 Load: 84.9 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.