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US 87 over Marias River

Chouteau County, Montana · rated Good in the 2025 National Bridge Inventory

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

US 87 over Marias River in Chouteau County, Montana, is rated in good condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the substructure, rated 7 (good condition) on the 0-9 scale.
It was built in 1988, making it 37 years old at the 2025 inventory.
It carries about 1,417 vehicles a day (traffic count year 2023).
Its listed owner is the state highway agency.
It is one of 25 of the 43 inventoried bridges in Chouteau County rated good (58.1%); 2 (4.7%) 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 stringer or multi-beam girder
Length	about 272 ft
Location	Loma
NBI structure number	P00010051+06521
Condition class	Good

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

Bridge	Built	Vehicles/day	Condition
US 87 over Abandoned Railroad	1974	1,727	Fair
Irr - US 87 over School Section Coulee	1970	1,694	Good
Irr - US 87 over Big Sandy Creek	1990	1,694	Good
S 80-13th St over Missouri River	1962	930	Poor
S 80 over RR	1953	849	Fair
S 80 over Shonkin Creek	2003	696	Good