Bridge conditions in Big Horn County, Montana
133 inventoried bridges · 5 rated poor · 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
Big Horn County tracks close to typical: 5 of its 133 inventoried bridges (3.8%) are rated poor, against a national rate of about 7%.
- 5 of the 133 bridges in Big Horn County, Montana, are rated in poor condition (3.8%) in the 2025 National Bridge Inventory, as of .
- 38 bridges (28.6%) are rated good and 90 (67.7%) fair.
- The median Big Horn County bridge was built in 1980.
- The busiest poor-rated bridge is Old Hwy 87 over Two Leggins Canal 0 (built 1931), carrying about 564 vehicles a day.
Good 28.6% · Fair 67.7% · Poor 3.8% of 133 bridges
Bridges rated poor
Every bridge in the county with a poor rating, busiest first. Poor means a major component is rated 4 or lower on FHWA's 0-9 scale; it is a repair flag, not a closure notice.
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Old Hwy 87 over Two Leggins Canal 0 | 1931 | 564 | Poor |
| Battlefield Road over Medicine Tail Coulee | 1938 | 150 | Poor |
| Soap Creek Rd over Big Horn Canal 009 | 1946 | 63 | Poor |
| Irr Bia Rte 205 over Upper Lodge Grass Creek | 1994 | 12 | Poor |
| Irr Bia Rte 226 over Black Canyon Creek | 1965 | 5 | Poor |
Busiest bridges in the county
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I 90 over Irrigation Canal | 1971 | 8,516 | Fair |
| Irr-s 47 over Int W Hardin I 90 | 1970 | 5,396 | Fair |
| Irr - I 90 over Int Dunmore | 1959 | 4,473 | Fair |
| Irr - I 90 over Int Dunmore | 1959 | 4,473 | Fair |
| Irr - I 90 over Bighorn River | 1971 | 4,258 | Good |
| Irr - I 90 over Bighorn River | 1971 | 4,258 | Fair |
| Irr - I 90 over Sarpy Road-s 384 | 1971 | 4,258 | Fair |
| Irr - I 90 over Sarpy Road-s 384 | 1971 | 4,258 | Fair |
| I 90 over Sep County Road | 1972 | 3,946 | Fair |
| I 90 over Sep County Road | 1972 | 3,946 | Fair |
Source: FHWA National Bridge Inventory, 2025. Counts cover inventoried highway bridges over 20 feet; ratings are reported by the state DOT.
All of Montana: Montana bridge conditions by county · every download on the data page.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.