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SH 21 over Mores Cr.;stierman Gulch

Boise County, Idaho · rated Good in the 2025 National Bridge Inventory

United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled August 20, 2026

SH 21 over Mores Cr.;stierman Gulch in Boise County, Idaho, is rated in good condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the deck, rated 7 (good condition) on the 0-9 scale.
It was built in 1990, making it 35 years old at the 2025 inventory.
It carries about 2,000 vehicles a day (traffic count year 2023).
Its listed owner is the state highway agency.
It is one of 45 of the 89 inventoried bridges in Boise County rated good (50.6%); 5 (5.6%) are rated poor.
A good rating means every major component - deck, superstructure, substructure, or culvert - is rated 7 or higher on FHWA's 0-9 scale: no more than minor problems.

Component ratings


Structure	Prestressed concrete multiple box beam
Length	about 69 ft
Location	8.3 S. Idaho City
NBI structure number	000000000012850
Condition class	Good

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

Bridge	Built	Vehicles/day	Condition
SH 55 over McLEOD WAY	2024	10,500	Good
SH 55 over Payette River	2021	8,800	Good
SH 55 over Power Canal	1994	8,800	Good
SH 55 over Uprr;horseshoe Bend Op	1971	7,800	Fair
SH 55 over Payette River	1971	7,800	Fair
SH 55 over S.fk.payette River	1955	7,300	Fair