21ST St. over Butte Arm Canal
Bonneville County, Idaho · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- 21ST St. over Butte Arm Canal in Bonneville County, Idaho, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 6 (satisfactory condition) on the 0-9 scale.
- It was built in 1955, making it 70 years old at the 2025 inventory.
- It carries about 2,025 vehicles a day (traffic count year 2023).
- Its listed owner is a city or municipal highway agency.
- It is one of 141 of the 213 inventoried bridges in Bonneville County rated fair (66.2%); 3 (1.4%) are rated poor.
- Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
- Its condition class and component ratings are unchanged from the 2024 inventory.
- Its most recent inspection on record is dated March 2023, on a 24-month routine inspection cycle.
- A fair rating means the lowest-rated major component scores 5 or 6 on FHWA's 0-9 scale: some deterioration or minor section loss, but the structure is sound. It is the middle class, not a warning.
View this bridge on a map → (43.47906, -112.03706)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 6 | 6 | Satisfactory condition |
| Superstructure | 7 | 7 | Good condition |
| Substructure | 7 | 7 | Good condition |
Bridge details
| Structure | Concrete stringer or multi-beam girder |
| Length | about 35 ft |
| Location | In Idaho FALLS;21ST St. |
| NBI structure number | 000000000031320 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | March 2023 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 8: foundations stable, scour above the top of the footing |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Idaho department of transportation.
Busiest bridges in Bonneville County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US 20 over Porter Canal | 1966 | 38,000 | Fair |
| US 20 Ebl & Wbl over Snake R.;johns Hole Br. | 1966 | 38,000 | Fair |
| US 20 over Sma 7096;RIVERSIDE Dr.ic | 1969 | 38,000 | Fair |
| US 20 over Sage Canal | 1970 | 34,500 | Fair |
| US 20 over UPRR | 1966 | 32,000 | Fair |
| US 20 Wbl & Ebl over Sma 7076;LINDSAY Blvd.ic | 1966 | 32,000 | Fair |
All bridges nearby: Bonneville County, ID bridge conditions · every bridge in Bonneville County · Idaho bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.