County profile · official public datasets

Williamson County, IL

201 public highway bridges tracked in the FHWA National Bridge Inventory: 67.2% rated Good, 29.4% Fair, 3.5% Poor.

201
Public bridges
67.2%
Good condition
3.5%
Poor condition

The verdict

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

Williamson County pairs a top-10% lowest Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

Top 7%
lowest Poor share in state
3.5%
Poor-condition share
201
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.

Williamson County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Williamson County ranks #7 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 3.5%). Williamson County, Illinois contains 201 public highway bridges. Roughly 67.2% are rated “Good,” 29.4% “Fair,” and 3.5% “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

201

Public highway bridges in Williamson County

Good condition

67.2%

135 of 201 rated 7-9

Fair condition

29.4%

59 of 201 rated 5-6

Poor condition

3.5%

7 of 201 rated 4 or below

In-state Poor-share rank

#7 of 102

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

Condition distribution

Share of 201 NBI-tracked bridges by lowest applicable component rating.

Good
67.2% (135)
Fair
29.4% (59)
Poor
3.5% (7)

Williamson County's Poor-condition bridges carry 59,625 vehicle crossings a day

That is 6.8% of the county's reported daily bridge traffic on 3.5% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 8,518 crossings a day against 2,662 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 200 of 201 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

25.9% of Williamson County's bridges have passed the 50-year mark

52 of the 201 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 67.2% 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 42.9% of the county's Poor-condition bridge traffic

ILL 13 EB over CRABORCHARD LAKE, built 1964, carries 25,600 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 7-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 59,625 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Williamson County's bridges were built

201 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1990s, when 43 of the county's bridges still in the inventory were built, which is 21.4% of those with a recorded year. That cohort is now 25 to 34 years old in the 2024 inventory. Its average build year is 1985, 6 years newer than the Illinois average of 1979.

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

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

The 5 Illinois counties nearest Williamson County in number of bridges, with their condition splits. Its 3.5% Poor share is the 1st-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 Williamson County and the 5 Illinois counties closest to it in inventory size
County Bridges Poor
Fulton County 210 21%
McDonough County 209 6.7%
Williamson County (this page) 201 3.5%
Warren County 199 7.5%
Crawford County 197 6.1%
Jo Daviess County 193 9.8%

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

Similar inventory size

Nearest county inventories outside IL (201 bridges here).

Similar average build year

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

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

All 201 Good 135 Fair 59 Poor 7

Good-condition bridges (135)

TR 428

Good

Over: S FORK SALINE RIVER

3MI SE OF MARION, Williamson, IL

Built 2000 Load: 32.4 t ADT: 25

TR 509

Good

Over: WOLF CREEK

5 MI S OF MARION, Williamson, IL

Built 2000 Load: 32.4 t ADT: 10

TR 664

Good

Over: TRIB TO GRASSSY CRK

1.2MI W OF STONEFORT, Williamson, IL

Built 2000 Load: 32.4 t ADT: 25

TR 269 E

Good

Over: TRIB TO WOLF CREEK

6 MI S OF MARION, Williamson, IL

Built 2001 Load: 32.4 t ADT: 100

ROCKY COMFORT RD

Good

Over: TRIB TO GRASSY LAKE

9MI S OF CARTERVILLE, Williamson, IL

Built 2002 Load: 32.4 t ADT: 350

TR 644

Good

Over: BRIAR CREEK

4 MI N OF STONEFORT, Williamson, IL

Built 2003 Load: 32.4 t ADT: 50

HARMONY CHURCH RD

Good

Over: TRIB TO POND CREEK

0.125 E. IL 37, Williamson, IL

Built 2003 Load: 32.4 t ADT: 800

TR 233

Good

Over: CRAB ORCHARD CREEK

1.5MI E IF PITTSBURG, Williamson, IL

Built 2003 Load: 32.4 t ADT: 275

TR 542

Good

Over: CRAB ORCHARD CREEK

1.2MI E OF PITTSBURG, Williamson, IL

Built 2003 Load: 32.4 t ADT: 200

TR 505 A

Good

Over: GRASSY CREEK

5 MI W PULLEYS MILL, Williamson, IL

Built 2005 Load: 32.4 t ADT: 175

PARTRIDGE RD

Good

Over: I.C.G. R.R.

1 MI. W. SALINE CO., Williamson, IL

Built 2008 Load: 32.4 t ADT: 50

NORTH BEND ROAD

Good

Over: HURRICANE CREEK

2 MI E OF HURST, Williamson, IL

Built 2006 Load: 32.4 t ADT: 100

TR 95

Good

Over: LITTLE HURRICANE CR

0.5 MI NORTH OF COLP, Williamson, IL

Built 2005 Load: 32.4 t ADT: 25

TR 268

Good

Over: WOLF CREEK

3 MI NW PULLEYS MILL, Williamson, IL

Built 2008 Load: 32.4 t ADT: 50

EWING ROAD

Good

Over: TURNER CREEK

3 M S. CRAB ORCHARD, Williamson, IL

Built 2011 Load: 32.4 t ADT: 125

SYCAMORE RD

Good

Over: CAMBRIA CREEK

1.5 MI W CAMBRIA, Williamson, IL

Built 2010 Load: 32.4 t ADT: 1,050

TR 603

Good

Over: BRUSHY CREEK

1 MI E CREAL SPRINGS, Williamson, IL

Built 2012 Load: 32.4 t ADT: 175

TR 538

Good

Over: LITTLE CRAB ORCHARD

1 MI W CRAB ORCHARD, Williamson, IL

Built 2012 Load: 32.4 t ADT: 250

TR 632

Good

Over: ROCK CREEK

3 MI E CRAB ORCHARD, Williamson, IL

Built 1976 Load: 32.4 t ADT: 325

VICKSBURG STREET

Good

Over: DRAINAGE DITCH

3 BLKS NORTH MAIN ST, Williamson, IL

Built 1979 Load: 32.4 t ADT: 400

COLLEGE & GRANITE

Good

Over: WEST END CREEK

MARION, Williamson, IL

Built 1989 Load: 32.4 t ADT: 800

BOYTON ST-FAU 9631

Good

Over: WEST END CREEK

MARION, Williamson, IL

Built 1997 Load: 32.4 t ADT: 5,000

MITCHELL ST

Good

Over: WEST END CREEK

MARION, Williamson, IL

Built 1997 Load: 32.4 t ADT: 75

LIBERTY STREET

Good

Over: WEST END CREEK

MARION, Williamson, IL

Built 1997 Load: 32.4 t ADT: 125

MONROE STREET

Good

Over: WEST END CREEK

MARION, Williamson, IL

Built 1997 Load: 32.4 t ADT: 150

HOLLAND AVENUE

Good

Over: WEST END CREEK

MARION, Williamson, IL

Built 1997 Load: 32.4 t ADT: 175

OLD CREAL SPRINGS

Good

Over: CRAB ORCHARD CREEK

SE SIDE OF MARION, Williamson, IL

Built 1999 Load: 32.4 t ADT: 1,900

ALLEY

Good

Over: WEST END CREEK

MARION, Williamson, IL

Built 1997 Load: 32.4 t ADT: 10

CS 1104-AUGUSTA DR

Good

Over: UNNAMED STREAM

KOKOPELLI SUBDVSION, Williamson, IL

Built 1996 Load: 32.4 t ADT: 125

FAU 9588-HERRIN ST

Good

Over: 17TH ST DITCH

0.31 MI W OF IL 148, Williamson, IL

Built 1999 Load: 32.4 t ADT: 7,000

FUTURE STREET

Good

Over: DRAINAGE DITCH

FUTURE S OF COLLEGE, Williamson, IL

Built 2007 Load: 32.4 t ADT: 375

GARDEN AVE

Good

Over: DITCH

0.65 MI E OF SKYLINE, Williamson, IL

Built 2015 Load: 32.4 t ADT: 1,900

FAS 1887

Good

Over: GRASSY CREEK

1 MI NW OF STONEFORT, Williamson, IL

Built 1990 Load: 32.7 t ADT: 300

WEST GATE ROAD

Good

Over: GRASSY CREEK

4.5 MILES SOUTH OF HQ, Williamson, IL

Built 2006 Load: 33.6 t ADT: 2

IL 37

Good

Over: TRIB TO LIMB BRANCH

1 MI S OF MARION, Williamson, IL

Built 2018 Load: 33.7 t ADT: 5,500

FAS 909 (UNMARKED)

Good

Over: DITCH

0.27 MI W OF MARION, Williamson, IL

Built 1993 Load: 34.0 t ADT: 5,700

CH 13-S.MARKET ST

Good

Over: MULE CREEK

AT SCL OF MARION, Williamson, IL

Built 1986 Load: 35.0 t ADT: 3,550

ILL 13

Good

Over: STREAM

ECL OF MARION, Williamson, IL

Built 1962 Load: 35.6 t ADT: 14,400

FAS 1900

Good

Over: GRASSY CREEK

7 MI S CARTERVILLE, Williamson, IL

Built 1942 Load: 35.6 t ADT: 1,950

CH 13-S MARKET ST

Good

Over: TRIB CRAB ORCHARD CR

SCL OF MARION, Williamson, IL

Built 1986 Load: 36.0 t ADT: 3,550

OGDEN ROAD

Good

Over: LITTLE WOLF CREEK

OGDEN RD WEST OF HWY 148, Williamson, IL

Built 1998 Load: 36.3 t ADT: 35

TR 548

Good

Over: POND CREEK

5 MILES N PITTSBURG, Williamson, IL

Built 1985 Load: 36.3 t ADT: 325

FAS 1887-CH 12

Good

Over: S FORK SALINE R OVFL

3.5 MI S CRABORCHARD, Williamson, IL

Built 1988 Load: 36.3 t ADT: 1,150

FAS1887-SARAVILLE

Good

Over: S FORK SALINE RIVER

4 MI S CRAB ORCHARD, Williamson, IL

Built 1997 Load: 36.3 t ADT: 1,150

CH 5

Good

Over: SOUTH FORKSALINE

6 MI SOUTHILL RTE 13, Williamson, IL

Built 1983 Load: 36.9 t ADT: 50

THE HILL AVE

Good

Over: I-57

0.47MI E HALFWAY RD, Williamson, IL

Built 2008 Load: 37.3 t ADT: 3,600

WOLF CREEK RD

Good

Over: IL 13

CRAINVILLE, Williamson, IL

Built 2017 Load: 37.9 t

TR 29-DEAN ROAD

Good

Over: POND CREEK TRIB

4 MI NE PITTSBURG, Williamson, IL

Built 1998 Load: 38.6 t ADT: 250

FAS 1887 (UNMARKED

Good

Over: STREAM E CRABORCHARD

E OF CRABORCHARD, Williamson, IL

Built 2005 Load: 38.9 t ADT: 550

TWP ROAD 601

Good

Over: GRASSY CREEK

4 MI E CREAL SPRINGS, Williamson, IL

Built 1986 Load: 38.9 t ADT: 175

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.