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.

pre-1900

1
1910s

1
1920s

4
1930s

2
1940s

2
1950s

4
1960s

1
1970s

9
1980s

43
1990s

35
2000s

23
2010s

6
2020s

1

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.

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	Good	Fair	Poor	Avg. built
Henderson County	142	33.1%	54.9%	12%	1985
Perry County	136	38.2%	54.4%	7.4%	1981
Kendall County	132	52.3%	35.6%	12.1%	1990
Massac County	132	43.9%	47.7%	8.3%	1980
Monroe County (this page)	132	59.1%	34.1%	6.8%	1986
Johnson County	118	58.5%	39%	2.5%	1979

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).

St. Joseph County, MI · 132 bridges
Otero County, NM · 132 bridges
Prince George County, VA · 132 bridges
Suffolk city County, VA · 132 bridges

Similar average build year

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

El Paso County, TX · avg 1986 · 783 bridges
Caddo County, LA · avg 1986 · 682 bridges
Weld County, CO · avg 1986 · 614 bridges
Polk County, IA · avg 1986 · 545 bridges

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

Fair-condition bridges (45)

Sort:

Monroe County Bridge Snapshot

Condition distribution

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

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

One structure carries 50.8% of the county's Poor-condition bridge traffic

How Monroe 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

Fair-condition bridges (45)

MAEYSTOWN RD

TR 114/ LRC RD.

BRICKEY RD TR 119

L ROAD TR 136

GOEDDELTOWN RO TR

ILL 159

FAI 255 NB/EB

FAI 255 SB/WB

CH 12

FAS 1857

HH ROAD TR 47

GALL RD FAU 9345

TR 145 S. FORK RD

MARTINI RDTR59

TR 96 "M" ROAD

TR133 BRANDT RD

FAS 1857

TR 145 S. FORK RD

TR 21 STEPPIG RD.

TR 170

TR 141 FULTS RD

GILMORE LK RD/ TR

TR 7

TR 56B / D ROAD

FAS 1857

GALL RD./ FAU 9345

FAS 1857

MS 5900A RAMSEY RD

Levee Road / MS 56

IL3NB-255WB Ramp A

ILL 3 NB

CH 5/FAS 857

ILL 159

ILL 156

FAI 255 EB

FAI 255WB

IL 3 SB

IL 156

TR 72

FAS 1857

IL3NB->255WB Rmp E

I 255 NB Ramp D

IL 156

Ramp to IL 3 SB

J ROAD/ TR 102

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