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I-39 & US 51 NB over Blackhawk Road

Winnebago 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 NB over Blackhawk Road in Winnebago 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 1981, making it 44 years old at the 2025 inventory.
It carries about 14,500 vehicles a day (traffic count year 2023).
Its listed owner is the state highway agency.
It is one of 291 of the 465 inventoried bridges in Winnebago County rated fair (62.6%); 32 (6.9%) 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	Steel stringer or multi-beam girder
Length	about 145 ft
Location	1.75 Mi S of US 20
NBI structure number	101014300000000
Condition class	Fair

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

Bridge	Built	Vehicles/day	Condition
I-39 & US 20 over Madigan Creek	1963	50,900	Fair
I-90 N B over US 20 Br	2009	36,350	Good
I-90 S B over US 20 Br	2009	36,350	Good
US 20 W B over Ill 251 (11TH St)	1960	36,000	Fair
I-90 over Stream	1958	34,100	Good
US 20 E B over Kishwaukee St.	1960	32,000	Fair