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I-39/US 51 over Mackinaw River

McLean County, Illinois · rated Fair in the 2025 National Bridge Inventory

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

I-39/US 51 over Mackinaw River in McLean County, Illinois, 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 1989, making it 36 years old at the 2025 inventory.
It carries about 18,700 vehicles a day (traffic count year 2023).
Its listed owner is the state highway agency.
It is one of 230 of the 625 inventoried bridges in McLean County rated fair (36.8%); 16 (2.6%) 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	Continuous steel stringer or multi-beam girder
Length	about 431 ft
Location	8.8 Mi N of I-55
NBI structure number	057020300000000
Condition class	Fair

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

Bridge	Built	Vehicles/day	Condition
I-55/74 (NB & SB) over Unnamed Creek	1991	42,100	Fair
I-55 Busn Lp NB & over Sugar CR & Bike Path	2000	41,100	Fair
Fai 74 over Ditch	1966	28,400	Good
I-55 & FAS294 over Stream	1976	25,400	Fair
I-55 Busn Loop over US 51 at Bloomington	1939	25,000	Fair
I-55 Busn Loop over Norfolk Southern Railway	1940	25,000	Poor