Total bridges
116
Public highway bridges in Cassia County
County profile · official public datasets
Cassia County, ID
116 public highway bridges tracked in the FHWA National Bridge Inventory: 15.5% rated Good, 84.5% Fair, 0% Poor.
- 116
- Public bridges
- 15.5%
- Good condition
- 0%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Cassia County pairs a top-5% lowest Poor-condition share among rated counties in the state with a newer average build year than the state inventory.
- Top 5%
- lowest Poor share in state
- 0%
- Poor-condition share
- 116
- public highway bridges
- 1984
- avg year built
Poor is an FHWA condition category from the lowest applicable component rating (4 or below), not a live crossing-safety or closure decision. Rankings cover counties with at least five public highway bridges.
Cassia County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Cassia County ranks #2 of 44 Idaho counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 0%). Cassia County, Idaho contains 116 public highway bridges. Roughly 15.5% are rated “Good,” 84.5% “Fair,” and 0% “Poor.” Poor means the lowest applicable deck, superstructure, substructure, or culvert rating is 4 or below on the 0–9 NBI scale. It is a condition category, not a live safety or closure decision.
Responsible agencies inspect covered bridges on risk-based intervals under current NBIS rules and submit inventory data to FHWA annually. The list below shows every NBI-tracked bridge in the county. Use the “Sort by” controls to change the ordering, and click any row for its reported inspection date, traffic count, and condition fields.
Source: FHWA National Bridge Inventory. See methodology for full definitions.
Good condition
15.5%
18 of 116 rated 7-9
Fair condition
84.5%
98 of 116 rated 5-6
Poor condition
0%
0 of 116 rated 4 or below
In-state Poor-share rank
#2 of 44
Among Idaho counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 116 NBI-tracked bridges by lowest applicable component rating.
Good 15.5% (18)
Fair 84.5% (98)
Poor 0% (0)
39.7% of Cassia County's bridges have passed the 50-year mark
46 of the 116 bridges with a recorded construction year were built in 1974 or earlier. Age alone is not a defect: a well-maintained older bridge can rate Good, and 15.5% of this county's inventory does. Even so, this older cohort is the population from which future Poor ratings are drawn, which is why the age profile below matters alongside the condition split above.
Cutoff derives from the 2024 release year minus a 50-year design life. Source: FHWA National Bridge Inventory, 2024 release.
When Cassia County's bridges were built
116 bridges with a recorded construction year, grouped by decade
- 1950s 3
1950–1959
3 bridges
- 1960s
1960–1969
27 bridges
- 1970s
1970–1979
31 bridges
- 1980s
1980–1989
18 bridges
- 1990s 7
1990–1999
7 bridges
- 2000s
2000–2009
14 bridges
- 2010s 10
2010–2019
10 bridges
- 2020s 6
2020–2029
6 bridges
What this shows Construction peaked in the 1970s, when 31 of the county's bridges still in the inventory were built, which is 26.7% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year is 1984, 5 years newer than the Idaho average of 1979.
How Cassia County compares with Idaho's closest counties by inventory size
The 5 Idaho counties nearest Cassia County in number of bridges, with their condition splits. Its 0% Poor share is the 1st-lowest of these 6. Its average build year of 1984 against a peer-group mean of 1979 is 5 years newer.
Showing the 5 closest of 43 Idaho counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Twin Falls County | 126 | 12.7% | 84.1% | 3.2% | 1973 |
| Bannock County | 124 | 33.1% | 62.1% | 4.8% | 1981 |
| Cassia County (this page) | 116 | 15.5% | 84.5% | 0% | 1984 |
| Latah County | 115 | 35.7% | 64.3% | 0% | 1978 |
| Lemhi County | 112 | 53.6% | 40.2% | 6.3% | 1988 |
| Jerome County | 110 | 10% | 80.9% | 9.1% | 1974 |
Each share is of that county's own total tracked bridges; peers are the counties with 5 or more bridges whose inventory size is closest to Cassia County's. Source: FHWA National Bridge Inventory, 2024 release.
Nationwide counties with similar inventory size or average build year
Two NBI-derived peer sets for Cassia County, both outside Idaho so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside ID (116 bridges here).
- Howard County, AR · 116 bridges
- Worth County, IA · 116 bridges
- Sheridan County, KS · 116 bridges
- Caldwell County, KY · 116 bridges
Similar average build year
Nearest mean year-built outside ID (1984 here).
- Hennepin County, MN · avg 1984 · 936 bridges
- Duval County, FL · avg 1984 · 831 bridges
- El Paso County, CO · avg 1984 · 686 bridges
- Bell County, TX · avg 1984 · 660 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
All bridges (116)
S 50 W POLE LN RD
GoodOver: J CANAL
5.8 S 0.1 W BURLEY, Cassia, ID
Built 1990 Load: 26.3 t ADT: 230
STC2739;ROCK CR RD
GoodOver: ROCK CREEK
17.8 S. HANSON, Cassia, ID
Built 1971 Load: 32.7 t ADT: 590
2200 S ROAD
GoodOver: WEST CANAL
1.7 S. 1.5 W. OAKLEY, Cassia, ID
Built 2023 Load: 32.7 t ADT: 20
S 400 W
GoodOver: G CANAL
4.0 W 0.7 S BURLEY, Cassia, ID
Built 1994 Load: 35.4 t ADT: 990
I 86 EBL
GoodOver: I 84 WBL
13.8 E BURLEY, Cassia, ID
Built 2020 Load: 36.3 t ADT: 18,000
SH 81
GoodOver: G CANAL
IN DECLO, Cassia, ID
Built 2013 Load: 38.2 t ADT: 1,900
WILSON AVE
GoodOver: EAST CANAL
IN OAKLEY, Cassia, ID
Built 2011 Load: 39.0 t ADT: 30
BASELINE ROAD
GoodOver: RAFT RIVER
0.2S 0.4W RAFT RIVER IC, Cassia, ID
Built 2019 Load: 40.2 t ADT: 100
S 1200 W
GoodOver: MILNER MAIN CANAL
12.0 W 1.4 S BURLEY, Cassia, ID
Built 2021 Load: 42.1 t ADT: 270
I 86 WBL
GoodOver: RAFT RIVER
28.1 E. BURLEY, Cassia, ID
Built 2019 Load: 44.7 t ADT: 3,850
650 EAST ROAD
GoodOver: H CANAL
3.7S 2.0W DECLO;450S-650E, Cassia, ID
Built 2022 Load: 45.7 t ADT: 90
S 350 E RD
GoodOver: J CANAL
7.0 S 3.5 E BURLEY, Cassia, ID
Built 2000 Load: 49.0 t ADT: 30
EAST MAIN STREET
GoodOver: EAST CANAL
IN OAKLEY, Cassia, ID
Built 2020 Load: 49.6 t ADT: 350
I 86 WB RAMP
GoodOver: I 84
12.7 E. HEYBURN, Cassia, ID
Built 2020 Load: 63.5 t ADT: 400
S 1050 E RD
GoodOver: J CANAL
2.0 E 0.75 S DECLO, Cassia, ID
Built 2000 Load: 63.5 t ADT: 30
STC 2842;E EY ROAD
GoodOver: RAFT RIVER
2.4 S. 6.4 E. ALMO, Cassia, ID
Built 2014 Load: 89.1 t ADT: 50
Read our methodology - how this data is sourced, computed, and verified.
Related
Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainBridges
Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.