Bridge conditions in Yellowstone County, Montana
290 inventoried bridges · 7 rated poor · 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
The federal inventory lists 290 bridges in Yellowstone County: 97 rated good, 186 fair, and 7 poor.
- 7 of the 290 bridges in Yellowstone County, Montana, are rated in poor condition (2.4%) in the 2025 National Bridge Inventory, as of .
- 97 bridges (33.4%) are rated good and 186 (64.1%) fair.
- The median Yellowstone County bridge was built in 1976.
- The busiest poor-rated bridge is Montana Ave over U1025-rr (built 1960), carrying about 8,576 vehicles a day.
Good 33.4% · Fair 64.1% · Poor 2.4% of 290 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 |
|---|---|---|---|
| Montana Ave over U1025-rr | 1960 | 8,576 | Poor |
| Montana Ave over U1024-25-rr | 1960 | 8,576 | Poor |
| Old Hwy 312 over Yellowstone River 170 | 1949 | 4,005 | Poor |
| S Shiloh Rd over Sep I 90 | 1959 | 3,188 | Poor |
| Old US 10 over Big Ditch 051 | 1932 | 2,489 | Poor |
| W I Rd over Custer Coulee 098 | 1962 | 100 | Poor |
| Anita Res Acc Rd over Anita Dam Spillway | 1937 | 10 | Poor |
Busiest bridges in the county
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I90 over MT Power RR Spur | 2023 | 29,488 | Good |
| I 90 over City County Drain Ditch | 1966 | 27,985 | Fair |
| King Ave W over Bbwa Canal | 1994 | 26,602 | Fair |
| Mullowney Ln over RR | 2007 | 23,980 | Good |
| Mullowney Ln over RR | 2007 | 23,980 | Fair |
| US 87 over Int Lockwood I 90 | 1966 | 23,199 | Fair |
| US 87 over RR | 1993 | 23,199 | Fair |
| US 87 over Yellowstone River | 1993 | 23,199 | Fair |
| Central Ave over Bbwa Canal | 1978 | 17,985 | Fair |
| Grand Ave over Bbwa Canal | 1981 | 15,881 | 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.