Total bridges
251
Public highway bridges in Lake County
County profile · official public datasets
Lake County, IL
251 public highway bridges tracked in the FHWA National Bridge Inventory: 37.1% rated Good, 53% Fair, 10% Poor.
- 251
- Public bridges
- 37.1%
- Good condition
- 10%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Lake County posts a higher-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.
- 71st
- of 102 on Poor share
- 10%
- Poor-condition share
- 251
- public highway bridges
- 1976
- 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.
Lake County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Lake County ranks #71 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 10%). Lake County, Illinois contains 251 public highway bridges. Roughly 37.1% are rated “Good,” 53% “Fair,” and 10% “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.
Good condition
37.1%
93 of 251 rated 7-9
Fair condition
53%
133 of 251 rated 5-6
Poor condition
10%
25 of 251 rated 4 or below
In-state Poor-share rank
#71 of 102
Among Illinois counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 251 NBI-tracked bridges by lowest applicable component rating.
Good 37.1% (93)
Fair 53% (133)
Poor 10% (25)
Lake County's Poor-condition bridges carry 142,235 vehicle crossings a day
That is 4.1% of the county's reported daily bridge traffic on 10% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 5,689 crossings a day against 12,971 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 250 of 251 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
47% of Lake County's bridges have passed the 50-year mark
118 of the 251 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 37.1% 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 21.6% of the county's Poor-condition bridge traffic
IL 120 EB over DES PLAINES RIVER, built 1959, carries 30,700 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 25-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 142,235 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Lake County's bridges were built
251 bridges with a recorded construction year, grouped by decade
- 1900s 1
1900–1909
1 bridges
- 1910s 7
1910–1919
7 bridges
- 1920s 14
1920–1929
14 bridges
- 1930s 9
1930–1939
9 bridges
- 1940s 3
1940–1949
3 bridges
- 1950s
1950–1959
44 bridges
- 1960s
1960–1969
33 bridges
- 1970s
1970–1979
19 bridges
- 1980s
1980–1989
21 bridges
- 1990s
1990–1999
36 bridges
- 2000s
2000–2009
37 bridges
- 2010s
2010–2019
21 bridges
- 2020s 6
2020–2029
6 bridges
What this shows Construction peaked in the 1950s, when 44 of the county's bridges still in the inventory were built, which is 17.5% of those with a recorded year. That cohort is now 65 to 74 years old in the 2024 inventory. Its average build year (1976) matches the Illinois average (1979).
How Lake County compares with Illinois's closest counties by inventory size
The 5 Illinois counties nearest Lake County in number of bridges, with their condition splits. Its 10% Poor share is the 4th-lowest of these 6. Its average build year of 1976 against a peer-group mean of 1977 is in line with the group.
Showing the 5 closest of 101 Illinois counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| DeKalb County | 261 | 40.6% | 46.4% | 13% | 1981 |
| Jefferson County | 260 | 47.7% | 46.2% | 6.2% | 1984 |
| Effingham County | 253 | 47.4% | 47.8% | 4.7% | 1974 |
| Lake County (this page) | 251 | 37.1% | 53% | 10% | 1976 |
| Piatt County | 246 | 62.2% | 31.7% | 6.1% | 1979 |
| Macoupin County | 242 | 36.4% | 45.9% | 17.8% | 1965 |
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 Lake 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 Lake County, both outside Illinois so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside IL (251 bridges here).
- Greene County, AR · 251 bridges
- Hopkins County, KY · 251 bridges
- Wayne County, NE · 251 bridges
- Fond du Lac County, WI · 251 bridges
Similar average build year
Nearest mean year-built outside IL (1976 here).
- Marion County, IN · avg 1976 · 958 bridges
- Mohave County, AZ · avg 1976 · 641 bridges
- Comanche County, OK · avg 1976 · 593 bridges
- Prince George's County, MD · avg 1976 · 576 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
All bridges (251)
Read our methodology - how this data is sourced, computed, and verified.
Related
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.