County profile · official public datasets

Cass County, IL

77 public highway bridges tracked in the FHWA National Bridge Inventory: 29.9% rated Good, 50.6% Fair, 19.5% Poor.

77
Public bridges
29.9%
Good condition
19.5%
Poor condition

The verdict

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

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

97th
of 102 on Poor share
19.5%
Poor-condition share
77
public highway bridges
1986
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.

Cass County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Cass County ranks #97 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 19.5%). Cass County, Illinois contains 77 public highway bridges. Roughly 29.9% are rated “Good,” 50.6% “Fair,” and 19.5% “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

77

Public highway bridges in Cass County

Good condition

29.9%

23 of 77 rated 7-9

Fair condition

50.6%

39 of 77 rated 5-6

Poor condition

19.5%

15 of 77 rated 4 or below

In-state Poor-share rank

#97 of 102

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

Condition distribution

Share of 77 NBI-tracked bridges by lowest applicable component rating.

Good
29.9% (23)
Fair
50.6% (39)
Poor
19.5% (15)

Cass County's Poor-condition bridges carry 10,975 vehicle crossings a day

That is 21.4% of the county's reported daily bridge traffic on 19.5% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 732 crossings a day against 948 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 77 of 77 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

26% of Cass County's bridges have passed the 50-year mark

20 of the 77 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 29.9% 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 51% of the county's Poor-condition bridge traffic

US 67 / IL 100 over ILLINOIS RIVER, built 1955, carries 5,600 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 10,975 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Cass County's bridges were built

77 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1980s, when 16 of the county's bridges still in the inventory were built, which is 20.8% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year is 1986, 7 years newer than the Illinois average of 1979.

Source FHWA National Bridge Inventory (year built) As of 2024 NBI release

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

The 5 Illinois counties nearest Cass County in number of bridges, with their condition splits. Its 19.5% Poor share is the 6th-lowest of these 6. Its average build year of 1986 against a peer-group mean of 1981 is 5 years newer.

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

Bridge inventory size and condition shares for Cass County and the 5 Illinois counties closest to it in inventory size
County Bridges Poor
Mason County 86 4.7%
Gallatin County 82 8.5%
Calhoun County 81 3.7%
Edwards County 79 7.6%
Cass County (this page) 77 19.5%
Brown County 71 14.1%

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

Similar inventory size

Nearest county inventories outside IL (77 bridges here).

Similar average build year

Nearest mean year-built outside IL (1986 here).

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

All 77 Good 23 Fair 39 Poor 15

All bridges (77)

IL 78

Good

Over: SANGAMON RIVER

.5 N CHANDLERVILLE, Cass, IL

Built 2011 Load: 36.3 t ADT: 1,450

TR 152

Good

Over: Conover Ck

0.65 mi S TR 151, Cass, IL

Built 2021 Load: 37.3 t ADT: 25

FAS 575

Good

Over: MIDDLE CREEK

4.5 M N NEWMANSVILLE, Cass, IL

Built 2010 Load: 40.2 t ADT: 500

CH 9 (FAS 580)

Good

Over: Mud Creek

1 MI W ARENZVILLE, Cass, IL

Built 2021 Load: 40.8 t ADT: 525

IL 78

Good

Over: LITTLE JOBS CREEK

4.3M N IL 125, Cass, IL

Built 1994 Load: 41.8 t ADT: 1,500

IL 78

Good

Over: PANTHER CREEK OVRFLW

SW SIDE CHANLERVILLE, Cass, IL

Built 2012 Load: 43.4 t ADT: 1,450

TR 7

Good

Over: Jobs Creek

3 MI W CHANDLERVILLE, Cass, IL

Built 2024 Load: 45.7 t ADT: 50

IL 78

Good

Over: Panther Creek

SW Chandlerville CL, Cass, IL

Built 2012 Load: 49.2 t ADT: 1,450

IL 125

Good

Over: TRIB TO LOST CREEK

2.2 M E BLUFFSRD, Cass, IL

Built 2009 Load: 49.2 t ADT: 3,500

IL 125

Good

Over: TRIB TO LOST CREEK

3.5 M E BLUFFS RD, Cass, IL

Built 2009 Load: 51.5 t ADT: 3,500

IL 125

Good

Over: LOST CREEK

BLUFF SPRG/5M E US67, Cass, IL

Built 2001 Load: 69.7 t ADT: 3,900

TR 32

Good

Over: PHELPS DITCH

3 M NE BEARDSTOWN, Cass, IL

Built 1970 Load: 84.9 t ADT: 50

TR 143

Poor

Over: LITTLE INDIAN CR.

2 MI SW PHILADELPHIA, Cass, IL

Built 1975 Load: 0.0 t ADT: 25

TR 124

Poor

Over: LITTLE INDIAN

3 MI SW PHILADELPHIA, Cass, IL

Built 1966 Load: 13.9 t ADT: 75

TR 224

Poor

Over: MIDDLE CRK.

4 MI N NEWMANSVILLE, Cass, IL

Built 1963 Load: 14.6 t ADT: 75

FAS 1577

Poor

Over: COX CREEK

1.5 MI WSW NEWMANSV., Cass, IL

Built 1982 Load: 17.8 t ADT: 425

FAS577

Poor

Over: LOST CREEK

3 MI E BEARDSTOWN, Cass, IL

Built 1936 Load: 19.1 t ADT: 650

TR 62

Poor

Over: LOST CREEK

1.5 MI E BLUFF SPR., Cass, IL

Built 1971 Load: 20.1 t ADT: 50

FAU 7779

Poor

Over: CLEAR CREEK

3 MI SE BEARDSTOWN, Cass, IL

Built 1968 Load: 22.7 t ADT: 1,650

TR 26

Poor

Over: INDIAN CREEK

2.5 MI NW ARENZVILLE, Cass, IL

Built 1971 Load: 22.7 t ADT: 275

US 67 / IL 100

Poor

Over: ILLINOIS RIVER

W EDGE BEARDSTOWN, Cass, IL

Built 1955 Load: 24.9 t ADT: 5,600

TR 2

Poor

Over: INDIAN CREEK

7MI W HAGENER, Cass, IL

Built 1989 Load: 26.6 t ADT: 50

TR 32

Poor

Over: LOST CREEK

2 MI NE BEARDSTOWN, Cass, IL

Built 1968 Load: 32.1 t ADT: 75

FAS 579

Poor

Over: PRAIRIE CREEK

1 MI S HAGENER, Cass, IL

Built 1960 Load: 32.7 t ADT: 1,750

FAS 573

Poor

Over: PANTHER CREEK

0.2 MI E OF ILL 78, Cass, IL

Built 1984 Load: 32.7 t ADT: 175

TR 68

Poor

Over: PRAIRIE CREEK

4MI NE ARENZVILLE, Cass, IL

Built 1978 Load: 37.3 t ADT: 50

TR 146

Poor

Over: PANTHER CREEK

1.5MI SE CHANDLERVIL, Cass, IL

Built 1997 Load: 38.6 t ADT: 50

Read our methodology - how this data is sourced, computed, and verified.

Related

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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.