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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 August 20, 2026

21ST St. over Butte Arm Canal in Bonneville County, Idaho, is rated in fair condition in the 2025 National Bridge Inventory (as of August 20, 2026).
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.
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.

Component ratings


Structure	Concrete stringer or multi-beam girder
Length	about 35 ft
Location	In Idaho FALLS;21ST St.
NBI structure number	000000000031320
Condition class	Fair

Source: FHWA National Bridge Inventory, 2025 data as reported by the Idaho department of transportation.

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