County profile · official public datasets

Winnebago County, IL

467 public highway bridges tracked in the FHWA National Bridge Inventory: 31.3% rated Good, 61.7% Fair, 7.1% Poor.

467
Public bridges
31.3%
Good condition
7.1%
Poor condition

The verdict

According to the Federal Highway Administration's 2024 National Bridge Inventory.

Winnebago County posts a better-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.

Top 42%
lowest Poor share in state
7.1%
Poor-condition share
467
public highway bridges
1978
avg year built

Poor is an FHWA condition category from the lowest applicable component rating (4 or below), not a live crossing-safety or closure decision. Rankings cover counties with at least five public highway bridges.

Winnebago County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Winnebago County ranks #43 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 7.1%). Winnebago County, Illinois contains 467 public highway bridges. Roughly 31.3% are rated “Good,” 61.7% “Fair,” and 7.1% “Poor.” Poor means the lowest applicable deck, superstructure, substructure, or culvert rating is 4 or below on the 0–9 NBI scale. It is a condition category, not a live safety or closure decision.

Responsible agencies inspect covered bridges on risk-based intervals under current NBIS rules and submit inventory data to FHWA annually. The list below shows every NBI-tracked bridge in the county. Use the “Sort by” controls to change the ordering, and click any row for its reported inspection date, traffic count, and condition fields.

Source: FHWA National Bridge Inventory. See methodology for full definitions.

Total bridges

467

Public highway bridges in Winnebago County

Good condition

31.3%

146 of 467 rated 7-9

Fair condition

61.7%

288 of 467 rated 5-6

Poor condition

7.1%

33 of 467 rated 4 or below

In-state Poor-share rank

#43 of 102

Among Illinois counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 467 NBI-tracked bridges by lowest applicable component rating.

Good
31.3% (146)
Fair
61.7% (288)
Poor
7.1% (33)

Winnebago County's Poor-condition bridges carry 180,060 vehicle crossings a day

That is 4.9% of the county's reported daily bridge traffic on 7.1% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 5,456 crossings a day against 6,482 for a Good-condition one. A Poor rating is a condition category, not a closure or a live safety judgement; it means the lowest applicable component rating is 4 or below.

Computed over the 467 of 467 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

49.5% of Winnebago County's bridges have passed the 50-year mark

231 of the 467 bridges with a recorded construction year were built in 1974 or earlier. Age alone is not a defect: a well-maintained older bridge can rate Good, and 31.3% of this county's inventory does. Even so, this older cohort is the population from which future Poor ratings are drawn, which is why the age profile below matters alongside the condition split above.

Cutoff derives from the 2024 release year minus a 50-year design life. Source: FHWA National Bridge Inventory, 2024 release.

One structure carries 14.1% of the county's Poor-condition bridge traffic

I-39 SB over HARRISON AVE, built 1963, carries 25,450 vehicles a day, the most of any Poor-rated structure here. The county's Poor-condition exposure is concentrated rather than evenly spread, so the 33-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 180,060 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Winnebago County's bridges were built

467 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1960s, when 121 of the county's bridges still in the inventory were built, which is 25.9% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1978) matches the Illinois average (1979).

Source FHWA National Bridge Inventory (year built) As of 2024 NBI release

How Winnebago County compares with Illinois's closest counties by inventory size

The 5 Illinois counties nearest Winnebago County in number of bridges, with their condition splits. Its 7.1% Poor share is the 2nd-lowest of these 6. Its average build year of 1978 against a peer-group mean of 1979 is in line with the group.

Showing the 5 closest of 101 Illinois counties eligible for comparison.

Bridge inventory size and condition shares for Winnebago County and the 5 Illinois counties closest to it in inventory size
County Bridges Poor
LaSalle County 528 12.3%
Madison County 523 8.4%
Vermilion County 494 7.3%
St. Clair County 486 9.1%
Winnebago County (this page) 467 7.1%
Sangamon County 466 6.2%

Each share is of that county's own total tracked bridges; peers are the counties with 5 or more bridges whose inventory size is closest to Winnebago County's. Source: FHWA National Bridge Inventory, 2024 release.

Nationwide counties with similar inventory size or average build year

Two NBI-derived peer sets for Winnebago County, both outside Illinois so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside IL (467 bridges here).

Similar average build year

Nearest mean year-built outside IL (1978 here).

Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.

All 467 Good 146 Fair 288 Poor 33

Good-condition bridges (146)

MAIN STREET

Good

Over: KINNIKINNICK CREEK

IN ROSCOE, Winnebago, IL

Built 2000 Load: 43.1 t ADT: 5,600

MORSAY DR

Good

Over: KEITH CREEK NORTH BR

0.03 MI E FAIRVIEW, Winnebago, IL

Built 1967 Load: 43.4 t ADT: 3,000

JACKSON STREET

Good

Over: UNNAMED STREAM

EAST EDGE PECATONICA, Winnebago, IL

Built 2000 Load: 43.7 t ADT: 750

STONERIDGE DR

Good

Over: SPRING CREEK

0.1 MI N SPRG CK RD, Winnebago, IL

Built 2011 Load: 44.4 t ADT: 100

MERIDIAN RD

Good

Over: ROCK CREEK

0.25 M S SIMPSON RD, Winnebago, IL

Built 1982 Load: 44.7 t ADT: 1,000

IL 251 NB

Good

Over: KILBUCK CREEK

.6 MI N. OGLE CO.LN., Winnebago, IL

Built 1989 Load: 45.0 t ADT: 4,450

COMLY ROAD

Good

Over: GROVE CREEK

2 MI S OF PECATONICA, Winnebago, IL

Built 1987 Load: 45.4 t ADT: 150

ROCKTON RD

Good

Over: DRY RUN CREEK

.5 MI E IL 251, Winnebago, IL

Built 2013 Load: 45.4 t ADT: 9,150

FOREST HILL ROAD

Good

Over: WILLOW CREEK

1.6 M S ILL 173, Winnebago, IL

Built 1981 Load: 45.7 t ADT: 11,300

MILL RD

Good

Over: I 90

.5 MI N OF CHERRY VA, Winnebago, IL

Built 2013 Load: 45.7 t ADT: 5,250

PERRYVILLE ROAD

Good

Over: N KISHWAUKEE RVR

0.4 MI N BLACKHAWK, Winnebago, IL

Built 1971 Load: 46.3 t ADT: 3,200

PRAIRIE HILL RD

Good

Over: DRY CREEK RUN

AT WILLOWBROOK RD, Winnebago, IL

Built 2007 Load: 46.7 t ADT: 4,050

MCCURRY RD

Good

Over: I-90 (N & W)

1 MI E OF ROSCOE, Winnebago, IL

Built 2006 Load: 46.7 t ADT: 3,900

TRAINER ROAD

Good

Over: SPRING CREEK

.25 MI N. OF SPRING BROOK, Winnebago, IL

Built 1991 Load: 47.0 t ADT: 1,100

PORTER ROAD

Good

Over: BR KENT CREEK

.33 M E MERIDIAN RD, Winnebago, IL

Built 1979 Load: 47.0 t ADT: 525

CH 52(WILLOW BROOK

Good

Over: BRANCH OF DRY CREEK

0.5 MI S ROCKTON RD, Winnebago, IL

Built 2004 Load: 47.6 t ADT: 5,650

NEWBURG RD

Good

Over: I-90

.10 W OF I-39, Winnebago, IL

Built 2008 Load: 49.2 t ADT: 9,350

MATERIAL AVE.

Good

Over: LOVES PARK CREEK

0.3 MI. S. WINDSOR, Winnebago, IL

Built 1992 Load: 49.6 t ADT: 2,300

S. CENTRAL AVENUE

Good

Over: S. BR. OF KENT CREEK

0.06 MI S OF PRESTON, Winnebago, IL

Built 1975 Load: 50.9 t ADT: 3,400

US 20 W B

Good

Over: E CHANNEL ROCK RIV

.7 MI E OF ILL 2, Winnebago, IL

Built 2015 Load: 51.8 t ADT: 32,000

PERRYVILLE RD

Good

Over: UNNAMED CREEK

0.03MI N OF IL 173, Winnebago, IL

Built 2004 Load: 51.8 t ADT: 7,800

MS-8810 Inter. Blv

Good

Over: Spring Creek

.5MI N RIVERSIDE BLV, Winnebago, IL

Built 2016 Load: 52.2 t ADT: 1,700

LINDEN RD

Good

Over: I 39 SB RAMP

OVER 39 SB RAMP, Winnebago, IL

Built 2023 Load: 52.5 t ADT: 25,200

LYFORD RD

Good

Over: KEITH CREEK

E. EDGE OF ROCKFORD, Winnebago, IL

Built 2017 Load: 53.5 t ADT: 2,750

PARK ACCESS RD

Good

Over: ROCK CUT SPILLWAY

ROCK CUT ST PARK, Winnebago, IL

Built 2019 Load: 53.5 t ADT: 775

US 20 W B

Good

Over: W CHANNEL ROCK RIV

.5 MI E OF ILL 2, Winnebago, IL

Built 2015 Load: 53.8 t ADT: 32,000

BORG WARNER ENTRAN

Good

Over: DRAINAGE WAY

.21 MI W 20TH ST, Winnebago, IL

Built 2016 Load: 53.8 t ADT: 2,050

PERRYVILLE ROAD

Good

Over: I-39

.75 S HARRISON AVE, Winnebago, IL

Built 2023 Load: 54.1 t ADT: 7,450

SPRING CREEK ROAD

Good

Over: SPRING CREEK

EAST OF ALPINE RAOD, Winnebago, IL

Built 2001 Load: 55.4 t ADT: 21,000

OLDE CREEK RD

Good

Over: KEITH CREEK

0.2 MI E PERRYVILLE, Winnebago, IL

Built 2003 Load: 55.7 t ADT: 6,200

MULFORD ROAD

Good

Over: S BR KEITH CR

0.3 MI N RT 20, Winnebago, IL

Built 1971 Load: 56.4 t ADT: 21,600

ATWOOD ROAD

Good

Over: MCDONALD CREEK

AT MCMICHAEL ROAD, Winnebago, IL

Built 1976 Load: 56.4 t ADT: 2,050

LOGISTICS PKWY

Good

Over: CREEK

.04MI N BLACKHAWK RD, Winnebago, IL

Built 2006 Load: 57.0 t ADT: 375

20TH ST

Good

Over: US 20

0.7 MI E OF ILL 251, Winnebago, IL

Built 2021 Load: 59.6 t ADT: 3,750

CAMPBELL ROAD

Good

Over: HUNGRY RUN CREEK

0.5 M E OF MOATE RD, Winnebago, IL

Built 1984 Load: 60.9 t ADT: 50

LUANNA DRIVE

Good

Over: PRIVATE LAKE

LAKE LEANNA SUB., Winnebago, IL

Built 1978 Load: 62.9 t ADT: 200

IL 75

Good

Over: CREEK

.06MI SW ROCKTON AVE, Winnebago, IL

Built 2010 Load: 66.1 t ADT: 2,250

TR-100 (Weldon Rd)

Good

Over: S BR OF KENT CRK

2 MI E OF WINNEBAGO, Winnebago, IL

Built 2018 Load: 67.1 t ADT: 800

NORTH ALPINE

Good

Over: BRANCH OF KEITH CRK

.5 MI N OF STATE ST, Winnebago, IL

Built 2018 Load: 69.7 t ADT: 19,000

BAKER RD

Good

Over: UNNAMED CREEK

0.3 MI E CROWLEY RD, Winnebago, IL

Built 1977 Load: 84.6 t ADT: 150

PERRYVILLE RD

Good

Over: UNNAMED CREEK

.6 MI. S. IL 173, Winnebago, IL

Built 1998 Load: 88.8 t ADT: 15,300

IL 75

Good

Over: DRAINAGE DITCH

0.36 E OF IL 70, Winnebago, IL

Built 2011 Load: 89.1 t ADT: 2,600

I-90

Good

Over: S KINNIKINNICK CREEK

1 MI E OF ROSCOE, Winnebago, IL

Built 1958 Load: 89.1 t ADT: 28,550

I-90

Good

Over: STREAM

1 MI S OF ILL 173, Winnebago, IL

Built 1958 Load: 89.1 t ADT: 30,700

I-90

Good

Over: N KINNIKINNICK CREEK

1 MI E OF ROSCOE, Winnebago, IL

Built 1958 Load: 93.3 t ADT: 28,550

I-90

Good

Over: STREAM

.6 MI S RIVERSIDE BL, Winnebago, IL

Built 1958 Load: 96.2 t ADT: 33,150

Read our methodology - how this data is sourced, computed, and verified.

Related

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Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainBridges

Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.