SR 9 over Black Slough
Whatcom County, Washington · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- SR 9 over Black Slough in Whatcom County, Washington, is rated in good condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 7 (good condition) on the 0-9 scale.
- It was built in 1900 and reconstructed in 1952, making it 125 years old at the 2025 inventory.
- It carries about 3,517 vehicles a day (traffic count year 2023).
- Its listed owner is the state highway agency.
- It is one of 157 of the 355 inventoried bridges in Whatcom County rated good (44.2%); 20 (5.6%) are rated poor.
- A good rating means every major component - deck, superstructure, substructure, or culvert - is rated 7 or higher on FHWA's 0-9 scale: no more than minor problems.
View this bridge on a map → (48.78222, -122.19444)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 7 | Good condition |
| Superstructure | 7 | Good condition |
| Substructure | 7 | Good condition |
Bridge details
| Structure | Continuous concrete slab |
| Length | about 87 ft |
| Location | 10.0 N Skagit Co |
| NBI structure number | 0004328B0000000 |
| Condition class | Good |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Washington department of transportation.
Busiest bridges in Whatcom County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I-5 over Orchard Dr/squalicum CR | 1958 | 39,925 | Fair |
| I-5 over Orchard Dr/squalicum CR | 1958 | 39,925 | Fair |
| I-5 over Meador Ave | 1957 | 38,169 | Fair |
| I-5 over Meador Ave | 1957 | 38,169 | Fair |
| I-5 over Iowa St | 1957 | 33,565 | Fair |
| I-5 over Whatcom Creek | 1957 | 33,565 | Fair |
All bridges nearby: Whatcom County, WA bridge conditions · every bridge in Whatcom County · Washington bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.