Stc 7787;PLYMOUTH over Boise River & Canal
Canyon County, Idaho · rated Poor in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Stc 7787;PLYMOUTH over Boise River & Canal in Canyon County, Idaho, is rated in poor condition in the 2025 National Bridge Inventory (as of ).
- It was built in 1922, making it 103 years old at the 2025 inventory.
- It carries about 2,100 vehicles a day (traffic count year 2023).
- A poor rating means at least one major component - deck, superstructure, or substructure - is rated 4 or lower on FHWA's 0-9 scale. It does not by itself mean the bridge is unsafe; bridges judged unsafe are closed or load-restricted by their owners.
View this bridge on a map → (43.68897, -116.68625)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 5 | Fair condition |
| Superstructure | 4 | Poor condition |
| Substructure | 4 | Poor condition |
Bridge details
| Structure | Steel through truss |
| Length | about 388 ft |
| Location | Caldwell Ncl |
| NBI structure number | 000000000026725 |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Idaho department of transportation.
All bridges nearby: Canyon County, ID bridge conditions · Idaho bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.