Bridge conditions in Jefferson County, Montana
136 inventoried bridges · 7 rated poor · 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
7 of the 136 bridges the federal inventory lists in Jefferson County are rated poor; the rest split 26 good and 103 fair.
- 7 of the 136 bridges in Jefferson County, Montana, are rated in poor condition (5.1%) in the 2025 National Bridge Inventory, as of .
- 26 bridges (19.1%) are rated good and 103 (75.7%) fair.
- The median Jefferson County bridge was built in 1976.
- The busiest poor-rated bridge is Mt 55 over Fish Creek (built 1953), carrying about 1,858 vehicles a day.
Good 19.1% · Fair 75.7% · Poor 5.1% of 136 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 |
|---|---|---|---|
| Mt 55 over Fish Creek | 1953 | 1,858 | Poor |
| Mt Hwy 2 over RR 061 | 1932 | 1,001 | Poor |
| Sleepy Hollow Ln over Prickly Pear Creek | 2010 | 100 | Poor |
| I 15 Frontage Rd over Cataract Creek 030 | 1933 | 100 | Poor |
| I 15 Frontage Rd over Basin Creek 041 | 1985 | 100 | Poor |
| E Elk Park Rd over Bison Creek 016 | 1927 | 100 | Poor |
| Mcclellean Ck Road over Mcclellan Creek | 1959 | 40 | Poor |
Busiest bridges in the county
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I 15 over Prickly Pear Creek | 1969 | 5,987 | Fair |
| I 15 over Prickly Pear Creek | 1969 | 5,987 | Fair |
| S 518 over Int Montana City-i 15 | 1968 | 5,885 | Good |
| I 90 over Int Cardwell-s 359 | 1968 | 5,599 | Fair |
| I 90 over Int Cardwell-s 359 | 1968 | 5,599 | Fair |
| I 90 Eastbound over Boulder River | 1968 | 5,599 | Good |
| I 90 Westbound over Boulder River | 1968 | 5,599 | Fair |
| I 90 over Sep County Road | 1969 | 5,599 | Fair |
| I 90 over Sep County Road | 1969 | 5,599 | Fair |
| I 90 Eastbound over Int Whitehall | 1966 | 5,175 | 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.