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Bridge conditions in Fallon County, Montana

38 inventoried bridges · 2 rated poor · 2025 National Bridge Inventory

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

Fallon County tracks close to typical: 2 of its 38 inventoried bridges (5.3%) are rated poor, against a national rate of about 7%.

2 of the 38 bridges in Fallon County, Montana, are rated in poor condition (5.3%) in the 2025 National Bridge Inventory, as of August 20, 2026.
17 bridges (44.7%) are rated good and 19 (50.0%) fair.
The median Fallon County bridge was built in 2005.
The busiest poor-rated bridge is S 7-main St N over Sandstone Creek (built 1941), carrying about 2,209 vehicles a day.

Good 44.7% · Fair 50.0% · Poor 5.3% of 38 bridges

Bridges rated poor

Every bridge in the county with a poor rating, busiest first. Poor means a major component is rated 4 or lower on FHWA's 0-9 scale; it is a repair flag, not a closure notice.

Bridge	Built	Vehicles/day	Condition
S 7-main St N over Sandstone Creek	1941	2,209	Poor
Cabin Creek Loop over Cabin Creek 057	1980	32	Poor

Busiest bridges in the county

Bridge	Built	Vehicles/day	Condition
Lake St over Baker Lake Overflow	2009	2,393	Good
S 7-main St N over Sandstone Creek	1941	2,209	Poor
US 12 over Drainage	1998	1,600	Fair
US 12 over Timber Creek	1998	825	Fair
US 12 over Sandstone Creek	1998	753	Fair
US 12 over RR	1968	696	Fair
US 12 over O`fallon Creek	1971	516	Fair
US 12 over Hay Creek	1932	516	Fair
US 12 over Sandstone Creek	1971	498	Fair
Main St S over Sandstone Creek	1964	119	Fair

Source: FHWA National Bridge Inventory, 2025. Counts cover inventoried highway bridges over 20 feet; ratings are reported by the state DOT.

All of Montana: Montana bridge conditions by county · every download on the data page.

Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.