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M-66 over Middle Branch River

Osceola County, Michigan · rated Good in the 2025 National Bridge Inventory

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

M-66 over Middle Branch River in Osceola County, Michigan, 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 1995, making it 30 years old at the 2025 inventory.
It carries about 1,685 vehicles a day (traffic count year 2007).
Its listed owner is the state highway agency.
It is one of 36 of the 103 inventoried bridges in Osceola County rated good (35.0%); 7 (6.8%) 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 79 ft
Location	2.2 Mi N of M-61
NBI structure number	000000000008593
Condition class	Good

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

Bridge	Built	Vehicles/day	Condition
US-131 NB over E Br Hersey River	1957	12,782	Fair
US-131 NB over Hersey Creek	1985	11,841	Fair
US-131 SB over Hersey Creek	1985	11,841	Fair
US-10 over Twin Creek	1997	11,184	Good
US-10 over Hersey River	1958	6,569	Fair
US-131 NB over Johnson Creek	1984	6,391	Fair