Checked
Idaho Bridge Conditions
Highway bridges longer than 20 feet in the 2025 National Bridge Inventory
Yearly inspection ratings. A poor rating does not mean a bridge is unsafe to use.
- Highway bridges
- 4,646
- Good condition
- 31.6%
- 1,468
- Poor condition
- 5.4%
- 250
- Weight-limited or closed
- 379
Bridges by county
| County | Bridges | Good | Poor | Weight-limited | Avg. year built |
|---|---|---|---|---|---|
| Ada County | 302 | 44.4% | 1% (3) | 1 | 1990 |
| Adams County | 87 | 31% | 9.2% (8) | 11 | 1976 |
| Bannock County | 128 | 37.5% | 4.7% (6) | 3 | 1983 |
| Bear Lake County | 34 | 41.2% | 0% (0) | 1 | 1985 |
| Benewah County | 48 | 35.4% | 6.3% (3) | 5 | 1984 |
| Bingham County | 263 | 16.7% | 3.4% (9) | 23 | 1975 |
| Blaine County | 96 | 28.1% | 4.2% (4) | 10 | 1979 |
| Boise County | 89 | 50.6% | 5.6% (5) | 5 | 1978 |
| Bonner County | 104 | 36.5% | 10.6% (11) | 7 | 1984 |
| Bonneville County | 213 | 32.4% | 1.4% (3) | 14 | 1978 |
| Boundary County | 84 | 31% | 13.1% (11) | 4 | 1983 |
| Butte County | 32 | 28.1% | 3.1% (1) | 3 | 1969 |
| Camas County | 62 | 27.4% | 11.3% (7) | 6 | 1979 |
| Canyon County | 291 | 29.6% | 2.1% (6) | 11 | 1985 |
| Caribou County | 45 | 26.7% | 4.4% (2) | 4 | 1985 |
| Cassia County | 117 | 20.5% | 0% (0) | 3 | 1984 |
| Clark County | 39 | 23.1% | 12.8% (5) | 7 | 1978 |
| Clearwater County | 88 | 43.2% | 6.8% (6) | 9 | 1973 |
| Custer County | 126 | 31.7% | 11.1% (14) | 11 | 1978 |
| Elmore County | 98 | 25.5% | 8.2% (8) | 9 | 1977 |
| Franklin County | 23 | 13% | 8.7% (2) | 4 | 1974 |
| Fremont County | 138 | 32.6% | 5.8% (8) | 18 | 1984 |
| Gem County | 57 | 24.6% | 5.3% (3) | 1 | 1976 |
| Gooding County | 80 | 27.5% | 6.3% (5) | 16 | 1969 |
| Idaho County | 216 | 40.3% | 6.9% (15) | 19 | 1976 |
| Jefferson County | 125 | 19.2% | 3.2% (4) | 9 | 1973 |
| Jerome County | 111 | 18% | 9% (10) | 11 | 1976 |
| Kootenai County | 159 | 32.1% | 4.4% (7) | 3 | 1985 |
| Latah County | 119 | 39.5% | 0.8% (1) | 13 | 1982 |
| Lemhi County | 114 | 57% | 7.9% (9) | 10 | 1988 |
| Lewis County | 21 | 57.1% | 4.8% (1) | 2 | 1991 |
| Lincoln County | 53 | 30.2% | 26.4% (14) | 13 | 1978 |
| Madison County | 80 | 32.5% | 0% (0) | 4 | 1982 |
| Minidoka County | 67 | 31.3% | 1.5% (1) | 0 | 1985 |
| Nez Perce County | 72 | 27.8% | 4.2% (3) | 17 | 1977 |
| Oneida County | 23 | 4.3% | 0% (0) | 0 | 1972 |
| Owyhee County | 49 | 32.7% | 8.2% (4) | 5 | 1976 |
| Payette County | 65 | 20% | 4.6% (3) | 4 | 1971 |
| Power County | 71 | 32.4% | 1.4% (1) | 3 | 1973 |
| Shoshone County | 261 | 23.4% | 10% (26) | 26 | 1972 |
| Teton County | 37 | 54.1% | 5.4% (2) | 2 | 1993 |
| Twin Falls County | 126 | 11.1% | 4% (5) | 16 | 1973 |
| Valley County | 153 | 47.1% | 6.5% (10) | 13 | 1982 |
| Washington County | 80 | 32.5% | 5% (4) | 9 | 1981 |
Frequently asked questions
- How many bridges in Idaho are in poor condition?
- In the 2025 National Bridge Inventory, 250 of 4,646 highway bridges in Idaho were rated poor (5.4% of rated bridges).
- Which Idaho counties have the most bridges in poor condition?
- Among counties with at least 30 bridges, the highest shares rated poor are Lincoln County (26.4%), Boundary County (13.1%), Clark County (12.8%), Camas County (11.3%), Custer County (11.1%).
Source: Federal Highway Administration, National Bridge Inventory · 2025 data