Total bridges
342
Public highway bridges in Stephenson County
County profile · official public datasets
Stephenson County, IL
342 public highway bridges tracked in the FHWA National Bridge Inventory: 61.1% rated Good, 36.3% Fair, 2.6% Poor.
- 342
- Public bridges
- 61.1%
- Good condition
- 2.6%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Stephenson County posts a top-5% lowest Poor-condition share among rated counties in the state across mid-size county bridge inventory.
- Top 5%
- lowest Poor share in state
- 2.6%
- Poor-condition share
- 342
- public highway bridges
- 1977
- 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.
Stephenson County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Stephenson County ranks #5 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 2.6%). Stephenson County, Illinois contains 342 public highway bridges. Roughly 61.1% are rated “Good,” 36.3% “Fair,” and 2.6% “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
61.1%
209 of 342 rated 7-9
Fair condition
36.3%
124 of 342 rated 5-6
Poor condition
2.6%
9 of 342 rated 4 or below
In-state Poor-share rank
#5 of 102
Among Illinois counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 342 NBI-tracked bridges by lowest applicable component rating.
Good 61.1% (209)
Fair 36.3% (124)
Poor 2.6% (9)
Stephenson County's Poor-condition bridges carry 3,350 vehicle crossings a day
That is 0.8% of the county's reported daily bridge traffic on 2.6% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 372 crossings a day against 631 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 340 of 342 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
40.4% of Stephenson County's bridges have passed the 50-year mark
138 of the 342 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 61.1% 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 43.3% of the county's Poor-condition bridge traffic
HANCOCK AVENUE over PECATONICA RIVER, built 1952, carries 1,450 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 9-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 3,350 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Stephenson County's bridges were built
342 bridges with a recorded construction year, grouped by decade
- pre-1900 2
Built before 1900
2 bridges
- 1900s 2
1900–1909
2 bridges
- 1910s 4
1910–1919
4 bridges
- 1920s 4
1920–1929
4 bridges
- 1930s 20
1930–1939
20 bridges
- 1940s 13
1940–1949
13 bridges
- 1950s
1950–1959
36 bridges
- 1960s
1960–1969
40 bridges
- 1970s
1970–1979
37 bridges
- 1980s
1980–1989
76 bridges
- 1990s
1990–1999
51 bridges
- 2000s
2000–2009
31 bridges
- 2010s 18
2010–2019
18 bridges
- 2020s 8
2020–2029
8 bridges
What this shows Construction peaked in the 1980s, when 76 of the county's bridges still in the inventory were built, which is 22.2% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year (1977) matches the Illinois average (1979).
How Stephenson County compares with Illinois's closest counties by inventory size
The 5 Illinois counties nearest Stephenson County in number of bridges, with their condition splits. Its 2.6% Poor share is the 1st-lowest of these 6. Its average build year of 1977 against a peer-group mean of 1983 is 6 years older.
Showing the 5 closest of 101 Illinois counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Macon County | 346 | 25.7% | 58.7% | 15.6% | 1984 |
| DuPage County | 344 | 37.5% | 54.4% | 8.1% | 1985 |
| Kankakee County | 344 | 40.1% | 53.5% | 6.4% | 1982 |
| Stephenson County (this page) | 342 | 61.1% | 36.3% | 2.6% | 1977 |
| Kane County | 336 | 48.2% | 45.5% | 6.3% | 1986 |
| Shelby County | 335 | 56.4% | 36.4% | 7.2% | 1978 |
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 Stephenson 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 Stephenson County, both outside Illinois so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside IL (342 bridges here).
- Winneshiek County, IA · 342 bridges
- Noble County, OK · 342 bridges
- Wayne County, IN · 343 bridges
- Norfolk County, MA · 343 bridges
Similar average build year
Nearest mean year-built outside IL (1977 here).
- San Diego County, CA · avg 1977 · 1,632 bridges
- King County, WA · avg 1977 · 1,238 bridges
- Riverside County, CA · avg 1977 · 1,117 bridges
- Shelby County, TN · avg 1977 · 1,077 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Fair-condition bridges (124)
HENDERSON ROAD-TR2
FairOver: US 20 FREEPORT BYPAS
1 MI EAST IL 26, Stephenson, IL
Built 1985 Load: 38.9 t ADT: 900
US20B WEST BOUND L
FairOver: US20 FREEPORT BYPASS
.3 MI E SPRINGFLD RD, Stephenson, IL
Built 1987 Load: 39.5 t ADT: 6,900
US 20 WB
FairOver: WICKHAM CREEK
4.0 MI W WINN CO LN, Stephenson, IL
Built 1983 Load: 40.2 t ADT: 12,700
US 20 EB
FairOver: WICKHAM CREEK
4 MI W. WINNEBAGO CO, Stephenson, IL
Built 1999 Load: 40.2 t ADT: 12,700
PEARL CITY RD.
FairOver: YELLOW CR. BR.
PEARL CITY, Stephenson, IL
Built 1940 Load: 40.5 t ADT: 2,650
IL 26
FairOver: DRAINAGE DITCH
2.6 MI N CEDARVILLE, Stephenson, IL
Built 1995 Load: 40.8 t ADT: 4,550
US20WB FREEPORT BY
FairOver: IL RT 75
NE OF FREEPORT, Stephenson, IL
Built 2004 Load: 42.1 t ADT: 6,100
ILL 73
FairOver: INDIAN CREEK
IN WINSLOW, Stephenson, IL
Built 1931 Load: 42.4 t ADT: 1,700
ILL RT 75
FairOver: ROCK RUN CREEK
1.3 MI E ROCK CITY, Stephenson, IL
Built 2011 Load: 43.1 t ADT: 3,300
IL 26
FairOver: YELLOW CREEK
S EDGE OF FREEPORT, Stephenson, IL
Built 1988 Load: 43.4 t ADT: 12,600
US 20 WB
FairOver: PECATONICA RIVER
NE OF FREEPORT, Stephenson, IL
Built 2008 Load: 43.4 t ADT: 6,800
US ROUTE 20 WB
FairOver: BIKE TRAIL
1.75 MI W OF IL 26, Stephenson, IL
Built 2011 Load: 44.1 t ADT: 6,150
US 20 BR
FairOver: SMALL CREEK
1.5 MI E FREEPORT, Stephenson, IL
Built 1956 Load: 45.0 t ADT: 7,000
E. CEDARVILLE RD.
FairOver: BROWN CREEK
2.0 MI SE DAKOTA, Stephenson, IL
Built 1940 Load: 45.0 t ADT: 950
US20 FREPORT BYPS
FairOver: PECATONICA RIVER
2.5 MI W OF IL 26, Stephenson, IL
Built 1987 Load: 46.3 t ADT: 6,150
US ROUTE 20 WB
FairOver: PECATONICA RIVER
2.5 MI W IL RTE 26, Stephenson, IL
Built 2011 Load: 46.7 t ADT: 6,150
US RT 20
FairOver: YELLOW CREEK
1.5 MI W ILL 73, Stephenson, IL
Built 1970 Load: 48.0 t ADT: 5,750
US 20 BR
FairOver: CN RR
0.5 MI E FREEPORT, Stephenson, IL
Built 1956 Load: 48.0 t ADT: 7,000
TOWER ROAD
FairOver: US20 FREEPORT BYPASS
NE OF FREEPORT, Stephenson, IL
Built 2004 Load: 49.2 t ADT: 125
IL 73
FairOver: YELLOW CREEK
0.5 MI N PEARL CITY, Stephenson, IL
Built 1992 Load: 53.1 t ADT: 2,350
US20 FREEPORT BYPA
FairOver: PECATONICA RIV TRIB
1.25 MI W OF IL 26, Stephenson, IL
Built 1987 Load: 53.1 t ADT: 6,150
US 20 BR
FairOver: YELLOW CREEK
1 MI E FREEPORT, Stephenson, IL
Built 1956 Load: 54.1 t ADT: 7,000
US 20 & PRIVATE RD
FairOver: SILVER CREEK TRIB
4 MI E OF FREEPORT, Stephenson, IL
Built 1959 Load: 54.1 t ADT: 12,700
US 20
FairOver: CN RAILROAD
2 MI. E. OF ELROY, Stephenson, IL
Built 2010 Load: 69.3 t ADT: 8,050
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.