County profile · official public datasets

Warren County, IL

199 public highway bridges tracked in the FHWA National Bridge Inventory: 69.3% rated Good, 23.1% Fair, 7.5% Poor.

199
Public bridges: 69.3%
Good condition: 7.5%
Poor condition

The verdict

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

Warren County pairs a better-than-median Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

Top 50%
lowest Poor share in state: 7.5%
Poor-condition share: 199
public highway bridges: 1985
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.

Warren County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Warren County ranks #51 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 7.5%). Warren County, Illinois contains 199 public highway bridges. Roughly 69.3% are rated “Good,” 23.1% “Fair,” and 7.5% “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

199

Public highway bridges in Warren County

Good condition

69.3%

138 of 199 rated 7-9

Fair condition

23.1%

46 of 199 rated 5-6

Poor condition

7.5%

15 of 199 rated 4 or below

In-state Poor-share rank

#51 of 102

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

Condition distribution

Share of 199 NBI-tracked bridges by lowest applicable component rating.

Good

69.3% (138)

Fair

23.1% (46)

Poor

7.5% (15)

Warren County's Poor-condition bridges carry 38,045 vehicle crossings a day

That is 19% of the county's reported daily bridge traffic on 7.5% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 2,536 crossings a day against 414 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 199 of 199 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

17.6% of Warren County's bridges have passed the 50-year mark

35 of the 199 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 69.3% 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 24.8% of the county's Poor-condition bridge traffic

US 34 IL 164 IL 1 over CEDAR CR TRIB, built 1964, carries 9,450 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 15-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 38,045 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

7
1910s

1
1930s

5
1940s

2
1950s

3
1960s

7
1970s

33
1980s

53
1990s

43
2000s

28
2010s

10
2020s

7

What this shows Construction peaked in the 1980s, when 53 of the county's bridges still in the inventory were built, which is 26.6% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year is 1985, 6 years newer than the Illinois average of 1979.

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

The 5 Illinois counties nearest Warren County in number of bridges, with their condition splits. Its 7.5% Poor share is the 5th-lowest of these 6. Its average build year of 1985 against a peer-group mean of 1980 is 5 years newer.

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

Bridge inventory size and condition shares for Warren County and the 5 Illinois counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Williamson County	201	67.2%	29.4%	3.5%	1985
Warren County (this page)	199	69.3%	23.1%	7.5%	1985
Crawford County	197	33%	60.9%	6.1%	1983
Jo Daviess County	193	46.1%	44%	9.8%	1973
De Witt County	192	57.3%	37%	5.7%	1980
Union County	192	54.7%	41.7%	3.6%	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 Warren 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 Warren County, both outside Illinois so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside IL (199 bridges here).

Montgomery County, AR · 199 bridges
Dallas County, IA · 199 bridges
Leake County, MS · 199 bridges
Neshoba County, MS · 199 bridges

Similar average build year

Nearest mean year-built outside IL (1985 here).

Hillsborough County, FL · avg 1985 · 840 bridges
Lancaster County, NE · avg 1985 · 661 bridges
Nueces County, TX · avg 1985 · 528 bridges
Grayson County, TX · avg 1985 · 513 bridges

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

All 199 Good 138 Fair 46 Poor 15

Good-condition bridges (138)

Sort:

Warren County Bridge Snapshot

Condition distribution

Warren County's Poor-condition bridges carry 38,045 vehicle crossings a day

17.6% of Warren County's bridges have passed the 50-year mark

One structure carries 24.8% of the county's Poor-condition bridge traffic

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

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

Good-condition bridges (138)

TR 20

TR 6

TR 45A

TR 22

TR 22

TR 59

TR 22

TR 50

TR 45

FAS 407 - CH 15

TR 206

TR 132

CAMERON RD-FAS 407

TR 48

TR 206

TR 132

CH 19

FAS 1408 - CH 17

CH-4 (FAS-410)

TR-254

TR 209

TR 179

OLD US 34

TR 162

TR 160

EB US 34

TR 87

US 34

TR 186

WB US 34

OLD US 67

TR 47

TR 166

FAS 406-CH 10

US 67

US 67

US 67

FAS 450-CH 19

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