County profile · official public datasets

Clinton County, IL

190 public highway bridges tracked in the FHWA National Bridge Inventory: 56.3% rated Good, 36.3% Fair, 7.4% Poor.

190
Public bridges: 56.3%
Good condition: 7.4%
Poor condition

The verdict

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

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

Top 48%
lowest Poor share in state: 7.4%
Poor-condition share: 190
public highway bridges: 1976
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.

Clinton County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Clinton County ranks #49 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 7.4%). Clinton County, Illinois contains 190 public highway bridges. Roughly 56.3% are rated “Good,” 36.3% “Fair,” and 7.4% “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

190

Public highway bridges in Clinton County

Good condition

56.3%

107 of 190 rated 7-9

Fair condition

36.3%

69 of 190 rated 5-6

Poor condition

7.4%

14 of 190 rated 4 or below

In-state Poor-share rank

#49 of 102

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

Condition distribution

Share of 190 NBI-tracked bridges by lowest applicable component rating.

Good

56.3% (107)

Fair

36.3% (69)

Poor

7.4% (14)

Clinton County's Poor-condition bridges carry 7,900 vehicle crossings a day

That is 1.9% of the county's reported daily bridge traffic on 7.4% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 564 crossings a day against 2,478 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 190 of 190 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

44.2% of Clinton County's bridges have passed the 50-year mark

84 of the 190 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 56.3% 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 34.2% of the county's Poor-condition bridge traffic

ALBERS RD/FAS 785 over GRASSY BRANCH, built 1973, carries 2,700 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 14-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 7,900 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

7
1910s

2
1920s

5
1930s

10
1940s

10
1950s

5
1960s

16
1970s

39
1980s

24
1990s

34
2000s

24
2010s

11
2020s

3

What this shows Construction peaked in the 1970s, when 39 of the county's bridges still in the inventory were built, which is 20.5% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1976) matches the Illinois average (1979).

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

The 5 Illinois counties nearest Clinton County in number of bridges, with their condition splits. Its 7.4% Poor share is the 4th-lowest of these 6. Its average build year of 1976 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 Clinton County and the 5 Illinois counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
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
Clinton County (this page)	190	56.3%	36.3%	7.4%	1976
Lawrence County	185	36.2%	41.1%	22.7%	1975
Saline County	185	71.4%	23.8%	4.9%	1985

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 Clinton 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 Clinton County, both outside Illinois so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside IL (190 bridges here).

Wapello County, IA · 190 bridges
Webster County, IA · 190 bridges
Bienville County, LA · 190 bridges
Lincoln County, MT · 190 bridges

Similar average build year

Nearest mean year-built outside IL (1976 here).

Marion County, IN · avg 1976 · 958 bridges
Mohave County, AZ · avg 1976 · 641 bridges
Comanche County, OK · avg 1976 · 593 bridges
Prince George's County, MD · avg 1976 · 576 bridges

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

All 190 Good 107 Fair 69 Poor 14

Good-condition bridges (107)

Sort:

Clinton County Bridge Snapshot

Condition distribution

Clinton County's Poor-condition bridges carry 7,900 vehicle crossings a day

44.2% of Clinton County's bridges have passed the 50-year mark

One structure carries 34.2% of the county's Poor-condition bridge traffic

How Clinton 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 (107)

TWP LINE/WESCLIN R

TR 184A/CREEK ROAD

TR 80/MUNICH ROAD

COVINGTON RD/TR 11

TR 27/EMERALD ROAD

TR 212/HAHN ROAD

TR 116

ILL 161

FLAT BRANCH RD-TR1

ILL 127

TR 90 FROGTOWN RD

TR 42/RANZ ROAD

SHATTUC RD/FAS 178

TR 28/TANK ROAD

FAI 64

FAI 64 WB

FAI 64 EB

IL 161

ILL 161

IL 161

IL 161

NEW US 50

TR 22/SPORTSMENS R

COLLEGE RD/TR 175

WESCLIN RD/TR 167

TR177/COURT ROAD

TR 223A/KASTEN ROA

TR 33/GOODINGSFORD

TR 9/LOUSE CREEK R

TR 211/AIRPORT ROA

TR 167/WESCLIN ROA

TR 3/KEYESPORT ROA

TR 96/TWIN LEVEE R

GIBBES RD/TR 59

TR 124/VAREL ROAD

HIGH LINE RD/TR 15

TR 255

TR 31 (IBERG RD)

TR 163/JUNCTION RD

TR 101 OLD STATE R

TR 179A OLD CARYLE

TR 153/HIGHLINE RD

TR 190/SCHNITZMEYE

TR 165/FELTON RD

BOND RD TR 1

FRICKER RD

MILL ROAD

JOLLIFF BRIDGE RD

TR 137 SAND RIDGE

TR 101/OLD STATE R

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