Bridge conditions in Sanilac County, Michigan
170 inventoried bridges · 25 rated poor · 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
Sanilac County has 25 bridges rated poor out of 170 inventoried, a 14.7% share that puts it well above the national rate of about 7%.
- 25 of the 170 bridges in Sanilac County, Michigan, are rated in poor condition (14.7%) in the 2025 National Bridge Inventory, as of .
- 50 bridges (29.4%) are rated good and 95 (55.9%) fair.
- The median Sanilac County bridge was built in 1983.
- The busiest poor-rated bridge is M-46 over Black River (built 1947), carrying about 5,462 vehicles a day.
Good 29.4% · Fair 55.9% · Poor 14.7% of 170 bridges
Bridges rated poor
Every bridge in the county with a poor rating, busiest first. Poor means a major component is rated 4 or lower on FHWA's 0-9 scale; it is a repair flag, not a closure notice.
Busiest bridges in the county
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| M-90 over Mills Creek | 2023 | 8,400 | Good |
| M-90 over Black River | 2023 | 8,400 | Good |
| M-25 over Mill Creek | 2016 | 7,775 | Good |
| M-46 over Black River | 1947 | 5,462 | Poor |
| M-90 over Spring Creek | 2000 | 5,001 | Good |
| M-90 over W Br Mills Creek | 2006 | 5,001 | Good |
| M-90 over E Br Mills Creek | 2000 | 5,001 | Good |
| Deckerville Road over Black River I/c Drain | 1985 | 4,630 | Good |
| M-19 over Elk Creek | 2000 | 4,553 | Fair |
| M-19 over Br of Elk Creek | 2000 | 4,553 | Good |
Source: FHWA National Bridge Inventory, 2025. Counts cover inventoried highway bridges over 20 feet; ratings are reported by the state DOT.
Every bridge in Sanilac County → - all 170, busiest first, each with its own condition record.
All of Michigan: Michigan bridge conditions by county · every download on the data page.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.