County profile · official public datasets

McLean County, IL

624 public highway bridges tracked in the FHWA National Bridge Inventory: 60.9% rated Good, 36.2% Fair, 2.9% Poor.

624
Public bridges: 60.9%
Good condition: 2.9%
Poor condition

The verdict

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

McLean County posts a top-10% lowest Poor-condition share among rated counties in the state across large county bridge inventory.

Top 6%
lowest Poor share in state: 2.9%
Poor-condition share: 624
public highway bridges: 1981
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.

McLean County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, McLean County ranks #6 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 2.9%). McLean County, Illinois contains 624 public highway bridges. Roughly 60.9% are rated “Good,” 36.2% “Fair,” and 2.9% “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

624

Public highway bridges in McLean County

Good condition

60.9%

380 of 624 rated 7-9

Fair condition

36.2%

226 of 624 rated 5-6

Poor condition

2.9%

18 of 624 rated 4 or below

In-state Poor-share rank

#6 of 102

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

Condition distribution

Share of 624 NBI-tracked bridges by lowest applicable component rating.

Good

60.9% (380)

Fair

36.2% (226)

Poor

2.9% (18)

McLean County's Poor-condition bridges carry 69,775 vehicle crossings a day

That is 3.7% of the county's reported daily bridge traffic on 2.9% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 3,876 crossings a day against 1,624 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 624 of 624 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

39.7% of McLean County's bridges have passed the 50-year mark

248 of the 624 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 60.9% 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 35.8% of the county's Poor-condition bridge traffic

I-55 BUSN LOOP over Norfolk Southern Railway, built 1940, carries 25,000 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 18-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 69,775 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

1
1920s

9
1930s

12
1940s

11
1950s

12
1960s

131
1970s

125
1980s

110
1990s

90
2000s

65
2010s

50
2020s

8

What this shows Construction peaked in the 1960s, when 131 of the county's bridges still in the inventory were built, which is 21% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1981) matches the Illinois average (1979).

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

The 5 Illinois counties nearest McLean County in number of bridges, with their condition splits. Its 2.9% Poor share is the 1st-lowest of these 6. Its average build year of 1981 against a peer-group mean of 1980 is in line with the group.

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

Bridge inventory size and condition shares for McLean County and the 5 Illinois counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Will County	649	43.1%	46.4%	10.5%	1983
McLean County (this page)	624	60.9%	36.2%	2.9%	1981
Livingston County	579	51.8%	39.9%	8.3%	1978
Iroquois County	570	46.5%	39.1%	14.4%	1980
LaSalle County	528	39.4%	48.3%	12.3%	1978
Madison County	523	49.3%	42.3%	8.4%	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 McLean 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 McLean County, both outside Illinois so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside IL (624 bridges here).

Steuben County, NY · 627 bridges
Westmoreland County, PA · 620 bridges
Contra Costa County, CA · 618 bridges
Brazoria County, TX · 618 bridges

Similar average build year

Nearest mean year-built outside IL (1981 here).

Franklin County, OH · avg 1981 · 922 bridges
Greenville County, SC · avg 1981 · 635 bridges
Montgomery County, OH · avg 1981 · 632 bridges
Shawnee County, KS · avg 1981 · 563 bridges

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

All 624 Good 380 Fair 226 Poor 18

Good-condition bridges (380)

Sort:

McLean County Bridge Snapshot

Condition distribution

McLean County's Poor-condition bridges carry 69,775 vehicle crossings a day

39.7% of McLean County's bridges have passed the 50-year mark

One structure carries 35.8% of the county's Poor-condition bridge traffic

How McLean 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 (380)

TR 137

TR 135

TR 440

TR 343A

TR 489

TR 352

TR 570 A

TR 43

TR4

TR 370

TR 536

TR 440

TR 559A

TR 424

TR 360

TR 236

SBI-2 (OLD 51)

TR 56

TR 404

TR 81

TR 168 A

TR 58

TR 94

FAS 471

TR 566

TR 328

TR 356

TR 296

FAU6384/ALEXANDER

TR 542

CHURCH ST

I-39/US 51 SB

TR 291

I-39/US 51 NB

TR 539

TR 299

TR 540

TR 568

TR 516

LINDEN/FAU 6405

TR 43

I-55 NB

TR 446

TR 124

TR 12

TR 16A

TR 16

TR 332

TR 532

I-39/US 51 SB

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