Total bridges
528
Public highway bridges in LaSalle County
County profile · official public datasets
LaSalle County, IL
528 public highway bridges tracked in the FHWA National Bridge Inventory: 39.4% rated Good, 48.3% Fair, 12.3% Poor.
- 528
- Public bridges
- 39.4%
- Good condition
- 12.3%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
LaSalle County posts a higher-than-median Poor-condition share among rated counties in the state across large county bridge inventory.
- 84th
- of 102 on Poor share
- 12.3%
- Poor-condition share
- 528
- public highway bridges
- 1978
- 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.
LaSalle County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, LaSalle County ranks #84 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 12.3%). LaSalle County, Illinois contains 528 public highway bridges. Roughly 39.4% are rated “Good,” 48.3% “Fair,” and 12.3% “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.
Good condition
39.4%
208 of 528 rated 7-9
Fair condition
48.3%
255 of 528 rated 5-6
Poor condition
12.3%
65 of 528 rated 4 or below
In-state Poor-share rank
#84 of 102
Among Illinois counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 528 NBI-tracked bridges by lowest applicable component rating.
Good 39.4% (208)
Fair 48.3% (255)
Poor 12.3% (65)
LaSalle County's Poor-condition bridges carry 81,630 vehicle crossings a day
That is 7.5% of the county's reported daily bridge traffic on 12.2% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 1,275 crossings a day against 2,002 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 525 of 528 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
39% of LaSalle County's bridges have passed the 50-year mark
206 of the 528 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 39.4% 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 13.1% of the county's Poor-condition bridge traffic
US 6 FAP 623 over FOX RIVER, built 1928, carries 10,700 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 65-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 81,630 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When LaSalle County's bridges were built
528 bridges with a recorded construction year, grouped by decade
- 1900s 2
1900–1909
2 bridges
- 1910s 3
1910–1919
3 bridges
- 1920s 12
1920–1929
12 bridges
- 1930s 36
1930–1939
36 bridges
- 1940s 14
1940–1949
14 bridges
- 1950s 31
1950–1959
31 bridges
- 1960s
1960–1969
76 bridges
- 1970s
1970–1979
74 bridges
- 1980s
1980–1989
112 bridges
- 1990s
1990–1999
64 bridges
- 2000s
2000–2009
49 bridges
- 2010s
2010–2019
49 bridges
- 2020s 6
2020–2029
6 bridges
What this shows Construction peaked in the 1980s, when 112 of the county's bridges still in the inventory were built, which is 21.2% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year (1978) matches the Illinois average (1979).
How LaSalle County compares with Illinois's closest counties by inventory size
The 5 Illinois counties nearest LaSalle County in number of bridges, with their condition splits. Its 12.3% Poor share is the 5th-lowest of these 6. Its average build year of 1978 against a peer-group mean of 1979 is in line with the group.
Showing the 5 closest of 101 Illinois counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Livingston County | 579 | 51.8% | 39.9% | 8.3% | 1978 |
| Iroquois County | 570 | 46.5% | 39.1% | 14.4% | 1980 |
| LaSalle County (this page) | 528 | 39.4% | 48.3% | 12.3% | 1978 |
| Madison County | 523 | 49.3% | 42.3% | 8.4% | 1979 |
| Vermilion County | 494 | 27.7% | 65% | 7.3% | 1979 |
| St. Clair County | 486 | 50% | 40.9% | 9.1% | 1977 |
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 LaSalle 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 LaSalle County, both outside Illinois so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside IL (528 bridges here).
- Merced County, CA · 528 bridges
- Nueces County, TX · 528 bridges
- New Castle County, DE · 527 bridges
- Marathon County, WI · 530 bridges
Similar average build year
Nearest mean year-built outside IL (1978 here).
- Orange County, CA · avg 1978 · 1,164 bridges
- Sumner County, KS · avg 1978 · 659 bridges
- Allen County, IN · avg 1978 · 613 bridges
- Buncombe County, NC · avg 1978 · 555 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Poor-condition bridges (65)
TR-18-A
PoorOver: SANDY CREEK
E 1ST N 1290, LaSalle, IL
Built 1963 Load: 32.7 t ADT: 10
TR-20A
PoorOver: SPRING CREEK
E 1ST N 3660, LaSalle, IL
Built 1977 Load: 33.4 t ADT: 100
IL 251/FAP 46
PoorOver: I-39/US 51
0.5 MI. N. IL 71, LaSalle, IL
Built 1986 Load: 34.7 t
TR 535
PoorOver: PRAIRE CREEK
N 14TH E 1950, LaSalle, IL
Built 1974 Load: 34.7 t ADT: 275
TR 203
PoorOver: SPRING CREEK
N 36TH E 150, LaSalle, IL
Built 1977 Load: 34.7 t ADT: 175
TWP RD TR 366
PoorOver: FAI 80
1.8 MI E OF ILL 71, LaSalle, IL
Built 1960 Load: 35.3 t ADT: 325
US 6 FAP 623
PoorOver: FOX RIVER
0.68 MI E OF ILL 23, LaSalle, IL
Built 1928 Load: 37.9 t ADT: 10,700
FAS 269 (CH 12)
PoorOver: FAI 39 US 51
3 MI N OF US 34, LaSalle, IL
Built 1977 Load: 38.2 t ADT: 325
WATER ST/N 4550TH
PoorOver: INDIAN CREEK
0.44 MI N OF US 34, LaSalle, IL
Built 1925 Load: 38.2 t ADT: 275
ILL 71 AT CEDAR PT
PoorOver: CEDAR CREEK
2.95 MI W OF US 51, LaSalle, IL
Built 1929 Load: 38.6 t ADT: 2,250
Coal Street
PoorOver: Coal run Creek
0.5 Mi S. of Ill. 18, LaSalle, IL
Built 1984 Load: 40.5 t ADT: 125
CH 52
PoorOver: LITTLE INDIAN CREEK
E. 1950 TH N 4775, LaSalle, IL
Built 1992 Load: 49.6 t ADT: 850
ILL 18 FAP 653
PoorOver: I-39/US 51
0.48 MI W OF IL 251, LaSalle, IL
Built 1988 Load: 50.5 t ADT: 2,650
TR 158
PoorOver: TOMAHAWK CREEK
E 9TH N 3960, LaSalle, IL
Built 1975 Load: 54.4 t ADT: 25
ILL 23 FAP 68
PoorOver: COVEL CREEK
3.35 MI S OF ILL 71, LaSalle, IL
Built 1953 Load: 56.1 t ADT: 5,550
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.