SR 9 over Black Slough
GoodWhatcom County, Washington · 10.0 N Skagit CO · Structure no. 0004328B0000000
- Built
- 1900
- 125 years old, rebuilt 1952
- Condition
- Good
- inspected July 2024
- Type
- Slab
- Concrete Continuous
- Length
- 88 ft
- 4 main spans
- Daily traffic
- 3,517
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
SR 9 over Black Slough is a concrete continuous slab carrying SR 9 over Black Slough in Whatcom County, Washington. It was built in 1900 and reconstructed in 1952, so it is 125 years old, older than the Washington average of 49.8 years.
The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.
It carries about 3,517 vehicles a day, roughly 15% of them trucks, projected to reach 4,774 by 2039. The structure is 88 ft (26.8 m) long and 40 ft wide. If it were closed, the detour would be 42.9 mi (69 km).
Location
Open in Google MapsCondition and inspection
All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 7 Good | Some minor problems. |
| Superstructure | 7 Good | Some minor problems. |
| Substructure | 7 Good | Some minor problems. |
| Channel and channel protection | 8 Very Good | No problems noted. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was SR 9 over Black Slough built?
It was built in 1900, making it 125 years old in 2025. It was reconstructed in 1952.
What condition is SR 9 over Black Slough in?
The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in July 2024.
How much traffic does SR 9 over Black Slough carry?
About 3,517 vehicles per day (2023 count), of which roughly 15% are trucks.
How long is SR 9 over Black Slough?
The structure is 88 ft (26.8 m) long with a longest span of 24 ft (7.3 m) and a deck 40 ft wide.
Who owns SR 9 over Black Slough?
It is owned by the State Highway Agency.