S 91 over Boulder River Overflow
Poor Condition89 years old2,133 vehicles/day
Location
| State | Montana |
| County | Sweet Grass |
| Location | Big Timber |
| Carries | S 91 |
| Crosses | Boulder River Overflow |
| Coordinates | 45.83461, -109.93522 |
Condition Ratings
| Overall Condition | Poor |
| Deck | 6 (Satisfactory) |
| Superstructure | 7 (Good) |
| Substructure | 4 (Poor) |
| Channel/Waterway | 8 (Very Good) |
| Scour Critical | 5 — Stable for scour |
Physical Characteristics
| Material | Wood or Timber |
| Design | Stringer/Multi-beam |
| Total Length | 25.6 ft (7.8 m) |
| Max Span | 24.6 ft (7.5 m) |
| Deck Width | 33.8 ft (10.3 m) |
| Deck Area | 80.3 sq m |
| Main Spans | 1 |
| Year Built | 1937 |
Traffic
| Avg Daily Traffic | 2,133 (2023) |
| Truck Traffic | 5% |
| Lanes On Bridge | 2 |
Inspection & Ownership
| Last Inspection | October 2024 |
| Inspection Frequency | Every 24 months |
| Owner | State Highway Agency |
| Historical Significance | Bridge is not eligible for the National Register |
| Structure Number | P00091002+06681 |