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)
I-39 OFF RAMP
FairOver: US 20 BYPASS
SW EDGE OF ROCKFORD, Winnebago, IL
Built 1981 Load: 53.1 t ADT: 4,550
I-39 SB
FairOver: FAP 301(US20 BYPASS)
0.4 MI W OF MULFORD, Winnebago, IL
Built 1981 Load: 53.1 t ADT: 12,600
I-39 & US 51 SB
FairOver: BLACKHAWK RD
1.75 MI S OF US 20, Winnebago, IL
Built 1981 Load: 53.1 t ADT: 14,500
I-39 & US 51 NB
FairOver: BLACKHAWK ROAD
1.75 MI S OF US 20, Winnebago, IL
Built 1981 Load: 53.1 t ADT: 14,500
US 20 E B
FairOver: E CHANNEL ROCK RIV
.7 MI E OF ILL 2, Winnebago, IL
Built 2014 Load: 53.5 t ADT: 32,000
KISHWAUKEE RD
FairOver: CANAL CREEK
0.8 MI NE CONDON RD, Winnebago, IL
Built 1979 Load: 54.1 t ADT: 4,550
PERRYVILLE RD
FairOver: SPRING CREEK
0.4 MI N SPRING BRK, Winnebago, IL
Built 1994 Load: 54.1 t ADT: 21,200
WELDON RD
FairOver: US RT 20
.2 MI S RT 20 BR, Winnebago, IL
Built 1961 Load: 54.8 t ADT: 800
CROCKETT ROAD
FairOver: UNNAMED CREEK
0.5 MI N BURR OAK RD, Winnebago, IL
Built 1968 Load: 54.8 t ADT: 950
US 20 WB
FairOver: PRAIRIE RD
1 MI W OF ILL 2, Winnebago, IL
Built 1964 Load: 56.7 t ADT: 20,400
US 20 EB
FairOver: PRAIRIE RD
1 MI W OF ILL 2, Winnebago, IL
Built 1964 Load: 56.7 t ADT: 20,400
FAI 90 S B
FairOver: DRY CREEK
1.0 MI SOUTH RT 75, Winnebago, IL
Built 2012 Load: 59.3 t ADT: 25,500
US 20 WB
FairOver: CUNNINGHAM RD.
1 MI E MERIDIAN RD, Winnebago, IL
Built 1964 Load: 59.6 t ADT: 14,600
US 20 EB
FairOver: CUNNINGHAM RD.
1 MI E MERIDIAN RD, Winnebago, IL
Built 1964 Load: 59.6 t ADT: 14,600
HARRISON ROAD
FairOver: STREAM
.9 MI N OF ILL 75, Winnebago, IL
Built 1973 Load: 59.6 t ADT: 350
US RT 20 WB
FairOver: US 20BR EB
3 MI W OF ROCKFORD, Winnebago, IL
Built 1961 Load: 59.9 t ADT: 11,400
I-39 RAMP
FairOver: LINDEN ROAD
.25 MI S OF US20, Winnebago, IL
Built 1981 Load: 59.9 t ADT: 4,650
SPRINGFIELD AVE
FairOver: S BR KENT CREEK
700 FT.S CUNNINGHAM, Winnebago, IL
Built 2002 Load: 61.6 t ADT: 7,700
US 20 W B
FairOver: CN RR
1.2 MI E MERIDIAN RD, Winnebago, IL
Built 1964 Load: 61.9 t ADT: 14,600
US 20 E B
FairOver: CN RR
1.2 MI E MERIDIAN RD, Winnebago, IL
Built 1964 Load: 62.2 t ADT: 14,600
I-90 S B
FairOver: BURR OAK RD
1 MI E OF ROSCOE, Winnebago, IL
Built 1958 Load: 62.2 t ADT: 28,550
MONTAGUE RD
FairOver: E BR MOSQUITO CREEK
2 MI W MERIDIAN RD, Winnebago, IL
Built 1983 Load: 64.2 t ADT: 3,300
I-90
FairOver: STREAM
.1 MI N RIVERSIDE BL, Winnebago, IL
Built 1958 Load: 68.0 t ADT: 30,700
MERIDIAN RD
FairOver: UNNAMED CREEK
0.3 MI N STATE ST, Winnebago, IL
Built 1968 Load: 69.3 t ADT: 4,150
BELVIDERE RD
FairOver: I-90
2.5 MI N ILL 173, Winnebago, IL
Built 1958 Load: 69.7 t ADT: 3,850
MERIDIAN RD
FairOver: US RT 20
1 MI S OF RT 20BR, Winnebago, IL
Built 1964 Load: 70.3 t ADT: 4,150
BEST ROAD
FairOver: PINK CREEK
0.7 MI S OF TRASK BR, Winnebago, IL
Built 1974 Load: 77.8 t ADT: 100
MERIDIAN RD
FairOver: S. BR. KENT CREEK
1.2 MI S OF 20 BR, Winnebago, IL
Built 1964 Load: 88.8 t ADT: 4,150
BRICK SCHOOL RD
FairOver: BEAVER RUN
0.7 MI E BARNINGHAM, Winnebago, IL
Built 1971 Load: 88.8 t ADT: 150
WHITE SCHOOL RD
FairOver: UNNAMED CREEK
0.4 MI N MCCURRY RD, Winnebago, IL
Built 1964 Load: 88.8 t ADT: 2,650
ALPINE ROAD
FairOver: DRAINAGE DITCH
0.1 M N WINDSOR, Winnebago, IL
Built 1972 Load: 88.8 t ADT: 16,800
SOUTH MAIN ST
FairOver: KENT CREEK
0.5 MI S OF STATE ST, Winnebago, IL
Built 1905 Load: 88.8 t ADT: 8,650
ILL 251
FairOver: SPRING CREEK RD
1.4 MI N WHITMAN ST, Winnebago, IL
Built 2012 Load: 89.1 t ADT: 29,700
RED OAK LANE
FairOver: S BR KEITH CREEK
0.03 M N GUILFORD, Winnebago, IL
Built 1980 Load: 89.1 t ADT: 325
I-90
FairOver: STREAM
.97 MI S OF BELV. RD, Winnebago, IL
Built 1958 Load: 89.1 t ADT: 28,550
US 20
FairOver: DRAINAGE DITCH
.2 MI E MERIDIAN RD, Winnebago, IL
Built 1964 Load: 99.9 t ADT: 14,600
US 20
FairOver: KENT CREEK
1.3 MI E MERIDIAN RD, Winnebago, IL
Built 1964 Load: 99.9 t ADT: 14,600
I-90
FairOver: STREAM
1 MI NE OF ROSCOE, Winnebago, IL
Built 1958 Load: 99.9 t ADT: 28,550
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.