County profile · official public datasets

Monroe County, IL

132 public highway bridges tracked in the FHWA National Bridge Inventory: 59.1% rated Good, 34.1% Fair, 6.8% Poor.

132
Public bridges
59.1%
Good condition
6.8%
Poor condition

The verdict

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

Monroe 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 40%
lowest Poor share in state
6.8%
Poor-condition share
132
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.

Monroe County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Monroe County ranks #41 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.8%). Monroe County, Illinois contains 132 public highway bridges. Roughly 59.1% are rated “Good,” 34.1% “Fair,” and 6.8% “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

132

Public highway bridges in Monroe County

Good condition

59.1%

78 of 132 rated 7-9

Fair condition

34.1%

45 of 132 rated 5-6

Poor condition

6.8%

9 of 132 rated 4 or below

In-state Poor-share rank

#41 of 102

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

Condition distribution

Share of 132 NBI-tracked bridges by lowest applicable component rating.

Good
59.1% (78)
Fair
34.1% (45)
Poor
6.8% (9)

Monroe County's Poor-condition bridges carry 8,075 vehicle crossings a day

That is 2% of the county's reported daily bridge traffic on 6.8% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 897 crossings a day against 1,664 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 132 of 132 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

12.9% of Monroe County's bridges have passed the 50-year mark

17 of the 132 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 59.1% 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 50.8% of the county's Poor-condition bridge traffic

FAU 9300 over CARR CREEK, built 1995, carries 4,100 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 8,075 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Monroe County's bridges were built

132 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1980s, when 43 of the county's bridges still in the inventory were built, which is 32.6% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year is 1986, 7 years newer than the Illinois average of 1979.

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

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

The 5 Illinois counties nearest Monroe County in number of bridges, with their condition splits. Its 6.8% Poor share is the 2nd-lowest of these 6. Its average build year of 1986 against a peer-group mean of 1983 is in line with the group.

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

Bridge inventory size and condition shares for Monroe County and the 5 Illinois counties closest to it in inventory size
County Bridges Poor
Henderson County 142 12%
Perry County 136 7.4%
Kendall County 132 12.1%
Massac County 132 8.3%
Monroe County (this page) 132 6.8%
Johnson County 118 2.5%

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

Similar inventory size

Nearest county inventories outside IL (132 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 132 Good 78 Fair 45 Poor 9

All bridges (132)

TR 28

Good

Over: LONG SLASH CREEK

4 MI SW COLUMBIA, Monroe, IL

Built 2010 Load: 32.4 t ADT: 125

TR 43 Merrimac Rd

Good

Over: Long Slash Creek

4 MI N of Valmeyer, Monroe, IL

Built 2012 Load: 32.4 t ADT: 50

TR 74 Gall Rd

Good

Over: Andys Run

1 Mi W. Waterloo, Monroe, IL

Built 2013 Load: 32.4 t ADT: 200

TR 32 Long Lake Rd

Good

Over: Maeystown Creek Trib

2 Mi SW Fults, Monroe, IL

Built 2014 Load: 32.4 t ADT: 25

TR-74 (Gall Road)

Good

Over: Andys Run Tributary

4 Mi NW of Waterloo, Monroe, IL

Built 2017 Load: 32.4 t ADT: 125

VALMYER RD/FAU 930

Good

Over: CARR CREEK

.3 MI W ILL 158, Monroe, IL

Built 1980 Load: 32.4 t ADT: 2,250

GERDERN DRIVE

Good

Over: PALMER CREEK

CITY OF COLUMBIA, Monroe, IL

Built 1995 Load: 32.4 t ADT: 400

ADMIRAL WEINEL BLV

Good

Over: WILSON CREEK

CITY OF COLUMBIA, Monroe, IL

Built 1998 Load: 32.4 t ADT: 750

FAU 9314

Good

Over: FOUNTAIN CREEK

WATERLOO, Monroe, IL

Built 2002 Load: 32.4 t ADT: 1,900

MSS 1324 STOCKEL L

Good

Over: TRIB TO FOUNTAIN CR

STOCKEL LN, Monroe, IL

Built 2004 Load: 32.4 t ADT: 475

RUECK ROAD

Good

Over: UN-NAMED CREEK

NE SEC9 T1 R10W, Monroe, IL

Built 2000 Load: 32.4 t ADT: 1,850

ADMIRAL TROST

Good

Over: WILSON CREEK

ADM TROST W IL 3, Monroe, IL

Built 2005 Load: 32.4 t ADT: 1,150

FAU 9315 Moore St.

Good

Over: Fountain Ck Trib

Waterloo, Monroe, IL

Built 2007 Load: 32.4 t ADT: 2,000

LEVEE RD TR 28

Good

Over: CARR CREEK

ROAD DIST NO.5, Monroe, IL

Built 1983 Load: 34.7 t ADT: 125

TR130 LL ROAD

Good

Over: HORSE CREEK

SEC 28 RD DIST 3, Monroe, IL

Built 1978 Load: 35.0 t ADT: 150

Ramp from IL 3 NB

Good

Over: PALMER CREEK

0.8 mi S of I-255, Monroe, IL

Built 1991 Load: 36.9 t ADT: 1,750

ILL 3

Good

Over: ROCKHOUSE CREEK

4 MI SE WATERLOO, Monroe, IL

Built 1995 Load: 39.9 t ADT: 6,950

TR 147 Faust Rd

Good

Over: Horse Ck

TR 147 1 mile N of Ames, Monroe, IL

Built 2022 Load: 42.1 t ADT: 125

Ramp to IL 3 SB

Good

Over: PALMER CRK Overflow

0.8 mi S of I-255, Monroe, IL

Built 1991 Load: 42.4 t ADT: 1,350

ADMIRAL TROST RD

Good

Over: WILSON CR. MSS 1296

CITY OF COLUMBIA, Monroe, IL

Built 2007 Load: 49.2 t ADT: 1,150

IL 158

Good

Over: IL 3

1 MI S COLUMBIA, Monroe, IL

Built 2012 Load: 63.5 t ADT: 9,550

ILL 3

Good

Over: Wilson Creek

0.9 mi N of IL 158, Monroe, IL

Built 1958 Load: 97.2 t ADT: 24,200

IL 3 Ramps F B E &

Good

Over: HILL LAKE CREEK

1.5 M N COLUMBIA, Monroe, IL

Built 1978 Load: 97.2 t ADT: 25,850

CH 12

Poor

Over: DRAINAGE CANAL

0.1 M W VALMEYER C L, Monroe, IL

Built 1935 Load: 0.0 t ADT: 400

MAEYSTOWN MSS 1030

Poor

Over: MAEYSTOWN CREEK

SW CL MAEYSTOWN, Monroe, IL

Built 1941 Load: 15.6 t ADT: 225

FAS-1858 (CH-12)

Poor

Over: Dennis Hollow

E CITY LIM VALMEYER, Monroe, IL

Built 1927 Load: 21.1 t ADT: 775

FAU 9300

Poor

Over: CARR CREEK

0.1M S COLUMBIA, Monroe, IL

Built 1995 Load: 24.9 t ADT: 4,100

MS 6190 (CARL ST)

Poor

Over: CREEK

200 SO. OF IL 3, Monroe, IL

Built 1972 Load: 24.9 t ADT: 1,150

TR139/OUTLET RD

Poor

Over: MONROE CITY CK

SEC 10 RD DISTRICT10, Monroe, IL

Built 1978 Load: 27.9 t ADT: 75

BLUFF RD/ FAS 1857

Poor

Over: FULTS CREEK

0.5 MI.SE OF FULTS, Monroe, IL

Built 1983 Load: 30.1 t ADT: 200

GALL RD/ FAU 9345

Poor

Over: CARR CREEK

COLUMBIA, Monroe, IL

Built 1978 Load: 33.4 t ADT: 725

TR 85 NIKE RD

Poor

Over: RICHLAND CREEK

1 MI E OF HECKER, Monroe, IL

Built 2001 Load: 38.2 t ADT: 425

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.