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M-21 over Maple River

Clinton County, Michigan · rated Fair in the 2025 National Bridge Inventory

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

M-21 over Maple River in Clinton County, Michigan, 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 1997, making it 28 years old at the 2025 inventory.
It carries about 6,505 vehicles a day (traffic count year 2007).
Its listed owner is the state highway agency.
It is one of 153 of the 215 inventoried bridges in Clinton County rated fair (71.2%); 34 (15.8%) 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	Prestressed concrete multiple box beam
Length	about 90 ft
Location	In Ovid
NBI structure number	000000000001891
Condition class	Fair

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

Bridge	Built	Vehicles/day	Condition
US-127 NB over Ferdun Creek	1957	88,500	Fair
US-127 SB over Coleman Rd	1971	41,300	Fair
US-127 NB over Coleman Rd	1971	41,300	Fair
I-96 over Husted & Landenburg Drn	1957	38,938	Fair
I-69 over Chandler Drain	1973	37,978	Fair
I-69 over Chandler Drain	1973	37,978	Fair