Mt HWY 91 over Poindexter Slough
FairBeaverhead County, Montana · 3M SW Dillon · Structure no. S00222002+07511
- Built
- 1936
- 89 years old
- Condition
- Fair
- inspected February 2025
- Type
- Tee Beam
- Concrete
- Length
- 77 ft
- 3 main spans
- Daily traffic
- 612
- 2023 count
- Owner
- State
- State Highway Agency
About this bridge
Mt HWY 91 over Poindexter Slough is a concrete tee beam carrying Mt HWY 91 over Poindexter Slough in Beaverhead County, Montana. It was built in 1936, so it is 89 years old, older than the Montana average of 47 years.
The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.
It carries about 612 vehicles a day, roughly 1% of them trucks, projected to reach 643 by 2043. The structure is 77 ft (23.5 m) long and 27 ft wide. If it were closed, the detour would be 6.8 mi (11 km).
Location
Open in Google MapsCondition and inspection
The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 7 Good | Some minor problems. |
| Superstructure | 6 Satisfactory | Structural elements show some minor deterioration. |
| Substructure | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
| Channel and channel protection | 7 Good | Some minor problems. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was Mt HWY 91 over Poindexter Slough built?
It was built in 1936, making it 89 years old in 2025.
What condition is Mt HWY 91 over Poindexter Slough in?
The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in February 2025.
How much traffic does Mt HWY 91 over Poindexter Slough carry?
About 612 vehicles per day (2023 count), of which roughly 1% are trucks.
How long is Mt HWY 91 over Poindexter Slough?
The structure is 77 ft (23.5 m) long with a longest span of 26 ft (7.9 m) and a deck 27 ft wide.
Who owns Mt HWY 91 over Poindexter Slough?
It is owned by the State Highway Agency.