County profile · official public datasets

Montgomery County, IL

261 public highway bridges tracked in the FHWA National Bridge Inventory: 52.1% rated Good, 40.6% Fair, 7.3% Poor.

261
Public bridges: 52.1%
Good condition: 7.3%
Poor condition

The verdict

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

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

Top 45%
lowest Poor share in state: 7.3%
Poor-condition share: 261
public highway bridges: 1977
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.

Montgomery County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Montgomery County ranks #46 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 7.3%). Montgomery County, Illinois contains 261 public highway bridges. Roughly 52.1% are rated “Good,” 40.6% “Fair,” and 7.3% “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

261

Public highway bridges in Montgomery County

Good condition

52.1%

136 of 261 rated 7-9

Fair condition

40.6%

106 of 261 rated 5-6

Poor condition

7.3%

19 of 261 rated 4 or below

In-state Poor-share rank

#46 of 102

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

Condition distribution

Share of 261 NBI-tracked bridges by lowest applicable component rating.

Good

52.1% (136)

Fair

40.6% (106)

Poor

7.3% (19)

Montgomery County's Poor-condition bridges carry 6,675 vehicle crossings a day

That is 2% of the county's reported daily bridge traffic on 7.3% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 351 crossings a day against 602 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 261 of 261 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

34.1% of Montgomery County's bridges have passed the 50-year mark

89 of the 261 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 52.1% 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 33.7% of the county's Poor-condition bridge traffic

CH 17 over I-55, built 1973, carries 2,250 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 19-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 6,675 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

16
1910s

2
1920s

6
1930s

7
1940s

6
1950s

9
1960s

18
1970s

40
1980s

64
1990s

37
2000s

39
2010s

15
2020s

2

What this shows Construction peaked in the 1980s, when 64 of the county's bridges still in the inventory were built, which is 24.5% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year (1977) matches the Illinois average (1979).

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

The 5 Illinois counties nearest Montgomery County in number of bridges, with their condition splits. Its 7.3% Poor share is the 3rd-lowest of these 6. Its average build year of 1977 against a peer-group mean of 1981 is in line with the group.

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

Bridge inventory size and condition shares for Montgomery County and the 5 Illinois counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Grundy County	269	40.5%	32.7%	26.8%	1984
Wayne County	266	54.1%	36.8%	9%	1982
DeKalb County	261	40.6%	46.4%	13%	1981
Montgomery County (this page)	261	52.1%	40.6%	7.3%	1977
Jefferson County	260	47.7%	46.2%	6.2%	1984
Effingham County	253	47.4%	47.8%	4.7%	1974

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

Similar inventory size

Nearest county inventories outside IL (261 bridges here).

Russell County, KS · 261 bridges
Vermilion County, LA · 261 bridges
Camden County, NJ · 261 bridges
Doña Ana County, NM · 261 bridges

Similar average build year

Nearest mean year-built outside IL (1977 here).

San Diego County, CA · avg 1977 · 1,632 bridges
King County, WA · avg 1977 · 1,238 bridges
Riverside County, CA · avg 1977 · 1,117 bridges
Shelby County, TN · avg 1977 · 1,077 bridges

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

All 261 Good 136 Fair 106 Poor 19

Good-condition bridges (136)

Sort:

Montgomery County Bridge Snapshot

Condition distribution

Montgomery County's Poor-condition bridges carry 6,675 vehicle crossings a day

34.1% of Montgomery County's bridges have passed the 50-year mark

One structure carries 33.7% of the county's Poor-condition bridge traffic

How Montgomery 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 (136)

TR 22

TR185

TR 8

TR 120

RAYMOND PAWNEE RD

TR 139A

TR 241

TR 149

TR 371

NOKOMIS RD

TR 113

TR 0271 A

NOKOMIS BLACKTOP

IL 16

IL 16

TR 101

TR 24

IL 16

TR 257

IL 16

IL 127

IL 127

FILLMORE TO RT 185

OLD & OLD OLD US 6

FAS 1746A(CH 9)

IL 127

NOKOMIS/FILLMORE R

IL 127

IL 127

IL 185

IL 127

IL 16

NOKOMIS RD

IL 16

IL 185

IL 185

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