Total bridges
467
Public highway bridges in Winnebago County
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.
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
- 1900s 3
1900–1909
3 bridges
- 1910s 3
1910–1919
3 bridges
- 1920s 9
1920–1929
9 bridges
- 1930s 12
1930–1939
12 bridges
- 1940s 7
1940–1949
7 bridges
- 1950s 48
1950–1959
48 bridges
- 1960s
1960–1969
121 bridges
- 1970s
1970–1979
55 bridges
- 1980s
1980–1989
64 bridges
- 1990s 44
1990–1999
44 bridges
- 2000s 42
2000–2009
42 bridges
- 2010s
2010–2019
52 bridges
- 2020s 7
2020–2029
7 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).
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.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| LaSalle County | 528 | 39.4% | 48.3% | 12.3% | 1978 |
| Madison County | 523 | 49.3% | 42.3% | 8.4% | 1979 |
| Vermilion County | 494 | 27.7% | 65% | 7.3% | 1979 |
| St. Clair County | 486 | 50% | 40.9% | 9.1% | 1977 |
| Winnebago County (this page) | 467 | 31.3% | 61.7% | 7.1% | 1978 |
| Sangamon County | 466 | 56.9% | 36.9% | 6.2% | 1981 |
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).
- Broome County, NY · 468 bridges
- Brown County, WI · 466 bridges
- Le Flore County, OK · 469 bridges
- Pecos County, TX · 470 bridges
Similar average build year
Nearest mean year-built outside IL (1978 here).
- Orange County, CA · avg 1978 · 1,164 bridges
- Sumner County, KS · avg 1978 · 659 bridges
- Allen County, IN · avg 1978 · 613 bridges
- Buncombe County, NC · avg 1978 · 555 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Fair-condition bridges (288)
TR-187 (KELLEY RD)
FairOver: SUMNER CREEK
0.5 MI E KLINGER RD, Winnebago, IL
Built 1948 Load: 8.7 t ADT: 125
TR-75 (OLIVER ROAD
FairOver: TUNNISON CREEK
0.5 MI N KNAPP ROAD, Winnebago, IL
Built 1961 Load: 10.7 t ADT: 50
WILLOWBROOK RD
FairOver: N KINNIKINNICK CR
0.2 M N ELEVATOR RD, Winnebago, IL
Built 1985 Load: 12.3 t ADT: 2,900
TR-83 (KNAPP ROAD)
FairOver: TUNNISON CREEK
0.5 MI W HARRISON RD, Winnebago, IL
Built 1961 Load: 12.3 t ADT: 75
TELEGRAPH RD
FairOver: UNNAMED CREEK
0.7 MI W EDDIE ROAD, Winnebago, IL
Built 1950 Load: 13.0 t ADT: 1,200
CAMPBELL ROAD
FairOver: N. BR. PINK CR.
0.7 M E OF CO. LINE, Winnebago, IL
Built 1951 Load: 13.6 t ADT: 50
20TH ST
FairOver: KEITH CREEK
0.02 MI S CHARLES, Winnebago, IL
Built 1928 Load: 15.6 t ADT: 7,750
MONTAGUE RD
FairOver: W BR MILL CR
1.27 MI E OF PEC. RD, Winnebago, IL
Built 1960 Load: 16.5 t ADT: 1,200
YALE BRIDGE RD
FairOver: RACCOON CREEK
AT CLOVER ROAD, Winnebago, IL
Built 1951 Load: 16.5 t ADT: 800
CUNNINGHAM RD
FairOver: GROVE CREEK
0.25 MI W CONGER RD, Winnebago, IL
Built 1960 Load: 17.5 t ADT: 250
MANCHESTER ROAD
FairOver: DRY RUN CREEK
1 MI E WILLOWBROOK, Winnebago, IL
Built 1960 Load: 17.5 t ADT: 675
MIDDLE ROAD
FairOver: DRY RUN CREEK
0.7 M E MANCHESTR RD, Winnebago, IL
Built 1965 Load: 18.1 t ADT: 250
JUDD ROAD
FairOver: UNNAMED CREEK
0.1 MI S CAMPBELL RD, Winnebago, IL
Built 1956 Load: 18.8 t ADT: 10
JEFFERSON ST
FairOver: ROCK RIV& MADISON ST
0.1 MI E OF N MAIN, Winnebago, IL
Built 1925 Load: 18.8 t ADT: 8,500
ROCK GROVE RD
FairOver: N. BR. OTTER CREEK
.25 MI E BEST ROAD, Winnebago, IL
Built 1988 Load: 19.1 t ADT: 425
AUBURN RD
FairOver: UNNAMED CREEK
2 MI NE OF WINNEBAGO, Winnebago, IL
Built 1936 Load: 19.1 t ADT: 1,250
PECATONICA RD
FairOver: GROVE CREEK
0.5 MI S US 20, Winnebago, IL
Built 1927 Load: 19.4 t ADT: 1,300
SAFFORD ROAD
FairOver: KENT CREEK
0.5 MI E SPRINGFIELD, Winnebago, IL
Built 1957 Load: 19.4 t ADT: 675
ROCKTON AVE
FairOver: BR MUD CREEK
1 MI S LATHAM RD, Winnebago, IL
Built 1956 Load: 19.8 t ADT: 675
CHARLES ST
FairOver: KEITH CREEK
1.5 MI W ALPINE RD, Winnebago, IL
Built 1940 Load: 20.1 t ADT: 14,700
HAMBORG ROAD
FairOver: S KINNIKINNICK CR
0.1 M S BURR OAK RD, Winnebago, IL
Built 1984 Load: 20.1 t ADT: 1,100
SPRINGFIELD AVE
FairOver: DRAINAGE DITCH
.4 MI. N. AUBURN ST., Winnebago, IL
Built 1960 Load: 20.4 t ADT: 7,600
EDDIE ROAD
FairOver: BR PECATONICA RIVER
AT FISH HATCHERY RD, Winnebago, IL
Built 1936 Load: 20.4 t ADT: 75
LOVE ROAD
FairOver: DRY RUN CREEK
0.5 MI S ROCKTON RD, Winnebago, IL
Built 1960 Load: 20.4 t ADT: 1,700
FOREST PRESERVE RD
FairOver: SUGAR CREEK
0.8 MI E HAULEY RD, Winnebago, IL
Built 1937 Load: 21.4 t ADT: 450
SEMINARY STREET
FairOver: CN RR
S CENTRAL ROCKFORD, Winnebago, IL
Built 1901 Load: 21.4 t ADT: 1,150
YALE BRIDGE RD
FairOver: SUGAR RIVER
1.7 MI E WHEELER RD, Winnebago, IL
Built 1953 Load: 21.7 t ADT: 325
CEMETERY ROAD
FairOver: UNAMD CREEK DITCH
2.64 MI E OF ILL 70, Winnebago, IL
Built 1954 Load: 21.7 t ADT: 575
ILL 2 S B
FairOver: ROCK RIVER
0.1 M S HONONEGAH RD, Winnebago, IL
Built 1966 Load: 22.4 t ADT: 8,550
IL 2 N B
FairOver: ROCK RIVER
0.1 M S HONONEGAH RD, Winnebago, IL
Built 1966 Load: 22.4 t ADT: 8,550
ROTHWELL ROAD
FairOver: BR OF CANAL CREEK
AT COUNTY LINE, Winnebago, IL
Built 1937 Load: 22.4 t ADT: 150
BURR OAK ROAD
FairOver: S KINNICKINNICK CR
0.3 MI S LOVESEE RD, Winnebago, IL
Built 1965 Load: 22.4 t ADT: 300
TAFT ROAD
FairOver: S.E. DRAINAGEWAY
0.1 MI E KISHWAUKEE, Winnebago, IL
Built 1967 Load: 22.4 t ADT: 100
BEST RD
FairOver: S BR OTTER CREEK
0.5 MI N DURAND RD, Winnebago, IL
Built 1955 Load: 22.7 t ADT: 3,000
PATTERSON ROAD
FairOver: N BR OTTER CREEK
0.5 MI S ROCK GROVE, Winnebago, IL
Built 1968 Load: 22.7 t ADT: 225
ALPINE RD
FairOver: SPRING CREEK
0.1 MI S OF SPRG CK, Winnebago, IL
Built 1955 Load: 22.7 t ADT: 20,900
MARSHALL ST
FairOver: S.E. DRAINAGEWAY
0.05 MI S HARRISON, Winnebago, IL
Built 1966 Load: 22.7 t ADT: 575
CHESTERFIELD AVE
FairOver: UNNAMED DRAIN. DITCH
0.01 MI N SAMUELSON, Winnebago, IL
Built 1965 Load: 22.7 t ADT: 300
BROOKE AND 9TH ST
FairOver: S.E. DRAINAGEWAY
AT BROOKE AND 9TH ST, Winnebago, IL
Built 1967 Load: 23.3 t ADT: 4,800
HARLMEM RD/BAUER P
FairOver: ROCK RIVER
0.65MI W IL 251, Winnebago, IL
Built 1993 Load: 23.7 t ADT: 12,000
WILLS AV
FairOver: S.E. DRAINAGEWAY
0.03 MI E OF 11TH ST, Winnebago, IL
Built 1968 Load: 23.7 t ADT: 500
INDEPENDENCE AVE
FairOver: S BR KENT CREEK
0.1 MI S OF PRESTON, Winnebago, IL
Built 1978 Load: 24.0 t ADT: 525
SPRING CREEK ROAD
FairOver: SPRING CREEK
0.5 MI E IL 251, Winnebago, IL
Built 1930 Load: 24.3 t ADT: 16,300
COUNTY LINE ROAD
FairOver: N. KINNICKINNICK CRK
1.1 MI N ELEVATOR RD, Winnebago, IL
Built 1960 Load: 24.3 t ADT: 800
YALE BRIDGE RD
FairOver: UNNAMED CREEK
0.2 MI E WHEELER RD, Winnebago, IL
Built 1932 Load: 24.3 t ADT: 325
KLINGER RD
FairOver: SUMNER CREEK
0.6 MI N KELLEY RD, Winnebago, IL
Built 1948 Load: 24.3 t ADT: 125
SAUNDERS RD
FairOver: COOLIDGE CREEK
0.5 MI E AHRENS ROAD, Winnebago, IL
Built 1957 Load: 24.3 t ADT: 800
DURAND RD
FairOver: S FORK OTTER CREEK
0.6 MI E BEST ROAD, Winnebago, IL
Built 1968 Load: 24.3 t ADT: 1,100
HARRISON ROAD
FairOver: KENT CREEK
0.7 N AUBURN ST, Winnebago, IL
Built 1957 Load: 24.3 t ADT: 100
MERIDIAN RD
FairOver: DRAINAGE
5 MI NE WINNEBAGO, Winnebago, IL
Built 1956 Load: 24.3 t ADT: 3,300
Read our methodology - how this data is sourced, computed, and verified.
Related
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.