County profile · official public datasets

Union County, IL

192 public highway bridges tracked in the FHWA National Bridge Inventory: 54.7% rated Good, 41.7% Fair, 3.6% Poor.

192
Public bridges: 54.7%
Good condition: 3.6%
Poor condition

The verdict

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

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

Top 8%
lowest Poor share in state: 3.6%
Poor-condition share: 192
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.

Union County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Union County ranks #8 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 3.6%). Union County, Illinois contains 192 public highway bridges. Roughly 54.7% are rated “Good,” 41.7% “Fair,” and 3.6% “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

192

Public highway bridges in Union County

Good condition

54.7%

105 of 192 rated 7-9

Fair condition

41.7%

80 of 192 rated 5-6

Poor condition

3.6%

7 of 192 rated 4 or below

In-state Poor-share rank

#8 of 102

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

Condition distribution

Share of 192 NBI-tracked bridges by lowest applicable component rating.

Good

54.7% (105)

Fair

41.7% (80)

Poor

3.6% (7)

Union County's Poor-condition bridges carry 26,150 vehicle crossings a day

That is 8.6% of the county's reported daily bridge traffic on 3.7% of its bridges: Poor-condition structures carry more traffic than their share of the inventory. Each Poor bridge averages 3,736 crossings a day against 887 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 190 of 192 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

34.4% of Union County's bridges have passed the 50-year mark

66 of the 192 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 54.7% 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 27.9% of the county's Poor-condition bridge traffic

FAI 57 SB & US 51 over FAS 926-BIG CREEK, built 1959, carries 7,300 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 26,150 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

5
1920s

2
1930s

6
1940s

4
1950s

26
1960s

17
1970s

20
1980s

39
1990s

20
2000s

27
2010s

19
2020s

7

What this shows Construction peaked in the 1980s, when 39 of the county's bridges still in the inventory were built, which is 20.3% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year (1981) matches the Illinois average (1979).

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

The 5 Illinois counties nearest Union County in number of bridges, with their condition splits. Its 3.6% Poor share is the 1st-lowest of these 6. Its average build year of 1981 against a peer-group mean of 1979 is in line with the group.

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

Bridge inventory size and condition shares for Union County and the 5 Illinois counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Warren County	199	69.3%	23.1%	7.5%	1985
Crawford County	197	33%	60.9%	6.1%	1983
Jo Daviess County	193	46.1%	44%	9.8%	1973
De Witt County	192	57.3%	37%	5.7%	1980
Union County (this page)	192	54.7%	41.7%	3.6%	1981
Clinton County	190	56.3%	36.3%	7.4%	1976

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

Similar inventory size

Nearest county inventories outside IL (192 bridges here).

Barbour County, AL · 192 bridges
El Dorado County, CA · 192 bridges
Santa Cruz County, CA · 192 bridges
Morgan County, CO · 192 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 192 Good 105 Fair 80 Poor 7

All bridges (192)

Sort:

Union County Bridge Snapshot

Condition distribution

Union County's Poor-condition bridges carry 26,150 vehicle crossings a day

34.4% of Union County's bridges have passed the 50-year mark

One structure carries 27.9% of the county's Poor-condition bridge traffic

How Union 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

All bridges (192)

TR 90

PRIV ENTR OFF ILL1

TR 276

TR 67

ILL 127 & ILL 146

TR 88B

CH 5

FAS 0926

TR 236A

TR 17

ILL 146

TR 287 SWAN POND R

TR 193 FRIENDSHIP

TR193

TR 130

TR 62

TR 141 CRAFT LN

TR 89

TR 19

FAI 57 RAMP 233 OF

FAS 0923

FAS 2936 (UNMARKED

TR 185

TR 0225

US 51

SBI 2B (UNMARKED)

TR 165

TR 49

FAS 926

TR 287

CH 20 NEW HOPE RD

FAI 57

ILL 127

US 51

ILL 127

ILL 127

FAS RT 924

FAS 924

TR 157

TR 133

TR 277

FAS 924

TR 276

FAS 1902

FAS 925

FAS 925-OLD CAPE R

TR 112

TR 267A-PUSH LANE

MT. PLEASANT RD

TR 221

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