County profile · official public datasets

DeKalb County, IL

261 public highway bridges tracked in the FHWA National Bridge Inventory: 40.6% rated Good, 46.4% Fair, 13% Poor.

261
Public bridges
40.6%
Good condition
13%
Poor condition

The verdict

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

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

86th
of 102 on Poor share
13%
Poor-condition share
261
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.

DeKalb County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, DeKalb County ranks #86 of 102 Illinois counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 13%). DeKalb County, Illinois contains 261 public highway bridges. Roughly 40.6% are rated “Good,” 46.4% “Fair,” and 13% “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 DeKalb County

Good condition

40.6%

106 of 261 rated 7-9

Fair condition

46.4%

121 of 261 rated 5-6

Poor condition

13%

34 of 261 rated 4 or below

In-state Poor-share rank

#86 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
40.6% (106)
Fair
46.4% (121)
Poor
13% (34)

DeKalb County's Poor-condition bridges carry 47,635 vehicle crossings a day

That is 8.1% of the county's reported daily bridge traffic on 13.1% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 1,401 crossings a day against 2,608 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 260 of 261 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

39.8% of DeKalb County's bridges have passed the 50-year mark

104 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 40.6% 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 28.6% of the county's Poor-condition bridge traffic

Annie Glidden Rd. over Watson Creek, built 1971, carries 13,600 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 34-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 47,635 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When DeKalb County's bridges were built

261 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1980s, when 45 of the county's bridges still in the inventory were built, which is 17.2% 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).

Source FHWA National Bridge Inventory (year built) As of 2024 NBI release

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

The 5 Illinois counties nearest DeKalb County in number of bridges, with their condition splits. Its 13% Poor share is the 5th-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 DeKalb County and the 5 Illinois counties closest to it in inventory size
County Bridges Poor
Grundy County 269 26.8%
Wayne County 266 9%
Montgomery County 261 7.3%
DeKalb County (this page) 261 13%
Jefferson County 260 6.2%
Effingham County 253 4.7%

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 DeKalb 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 DeKalb 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).

Similar average build year

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

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

All 261 Good 106 Fair 121 Poor 34

Poor-condition bridges (34)

NEW LEBANON RD

Poor

Over: COON CREEK

3130N 1800E, DeKalb, IL

Built 1964 Load: 0.0 t ADT: 150

ANDERLAND ROAD

Poor

Over: N BR KISHWAUKEE RV

1675N 600E, DeKalb, IL

Built 1960 Load: 0.0 t ADT: 100

WHEELER RD

Poor

Over: TRIMBLE RUN

3550N 140E, DeKalb, IL

Built 1964 Load: 17.8 t ADT: 175

PEARL ST

Poor

Over: SO BR KISHWAUKEE RV

3215N 540E, DeKalb, IL

Built 1949 Load: 19.4 t ADT: 1,000

AIRPORT RD

Poor

Over: UNION DITCH #1

1985N 1565E, DeKalb, IL

Built 1947 Load: 19.4 t ADT: 900

TR-71 (ALDRICH RD)

Poor

Over: S BR KISHWAUKEE RV

2850N 1185E, DeKalb, IL

Built 1950 Load: 21.7 t ADT: 75

NEW LEBANON RD

Poor

Over: COON CREEK

3460N 1790E, DeKalb, IL

Built 1969 Load: 24.3 t ADT: 100

HAUMESSER ROAD

Poor

Over: BRNCH KISHWAUKEE RV

1550N 400E, DeKalb, IL

Built 1968 Load: 26.2 t ADT: 10

PRATT ROAD/ MS 089

Poor

Over: SOMONAUK CREEK

245N 1565E, DeKalb, IL

Built 1967 Load: 27.5 t ADT: 600

HARTMAN ROAD

Poor

Over: UNION DRAINAGE DITCH

2070N 1650E, DeKalb, IL

Built 1971 Load: 28.8 t ADT: 100

SHABBONA GROVE ROA

Poor

Over: INDIAN CREEK

680N 200E, DeKalb, IL

Built 1976 Load: 28.8 t ADT: 75

FAU5336 (LUCINDA A

Poor

Over: SO BR KISHWAUKEE RIV

0.7 E. Annie Glidden, DeKalb, IL

Built 1954 Load: 28.8 t ADT: 2,650

GLIDDEN RD

Poor

Over: LEE SLOUGH CREEK

2955N 850E, DeKalb, IL

Built 1997 Load: 29.5 t ADT: 3,550

PRITCHARD RD

Poor

Over: W BR LITTLE ROCK CRE

1035N 1700E, DeKalb, IL

Built 1967 Load: 29.5 t ADT: 350

GOBLE ROAD

Poor

Over: BR OF INDIAN CREEK

455N 100E, DeKalb, IL

Built 1985 Load: 29.8 t ADT: 25

GOV. BEVERIDGE HWY

Poor

Over: BUCK BRANCH

135N 1400E, DeKalb, IL

Built 1954 Load: 30.1 t ADT: 275

IL 72 FAP 553

Poor

Over: OWENS CREEK

1.3 MI W OF KIRKLAND, DeKalb, IL

Built 1982 Load: 30.5 t ADT: 2,150

NEW LEBANON RD

Poor

Over: COON CREEK

3230N 1790E, DeKalb, IL

Built 1965 Load: 30.5 t ADT: 150

TR-96 (ANDERLAND R

Poor

Over: SO BR KISHWAUKEE RV

1480N 600E, DeKalb, IL

Built 1972 Load: 30.5 t ADT: 25

WATSON RD

Poor

Over: LITTLE INDIAN CREEK

600N 805E, DeKalb, IL

Built 1980 Load: 30.8 t ADT: 25

FAS-96 (Somonauk R

Poor

Over: Buck Br Somonauk Cr

110N 1460E, DeKalb, IL

Built 1996 Load: 31.8 t ADT: 3,250

SUYDAM ROAD

Poor

Over: PAW PAW CREEK

180N 200E, DeKalb, IL

Built 1983 Load: 32.1 t ADT: 200

MOTEL ROAD

Poor

Over: BR S BR KISHWAUKEE R

2610N 1200E, DeKalb, IL

Built 1980 Load: 32.7 t ADT: 525

HOWISON RD

Poor

Over: LITTLE ROCK CREEK

1210N 1200E, DeKalb, IL

Built 1961 Load: 32.7 t ADT: 275

IL 64 FAP 17

Poor

Over: DRAINAGE DITCH

2.3 MI W SYCAMORE, DeKalb, IL

Built 1937 Load: 33.0 t ADT: 4,500

WATERMAN ROAD

Poor

Over: BR OF SOMONAUK CREEK

1015N 900E, DeKalb, IL

Built 1985 Load: 33.0 t ADT: 425

FAS-176 (Perry Rd)

Poor

Over: Br of Battle Creek

1500N 1540E, DeKalb, IL

Built 1990 Load: 33.4 t ADT: 2,150

CHICAGO RD

Poor

Over: LITTLE INDIAN CREEK

4 MI S OF WATERMAN, DeKalb, IL

Built 2003 Load: 34.7 t ADT: 1,000

Annie Glidden Rd.

Poor

Over: Watson Creek

0.5mi. N. of 38, DeKalb, IL

Built 1971 Load: 36.3 t ADT: 13,600

GLIDDEN RD

Poor

Over: LEE SLOUGH CREEK

3120N 850E, DeKalb, IL

Built 1997 Load: 36.9 t ADT: 3,150

IL 23

Poor

Over: DEER CREEK TRIB.

1 MI N JCT ILL 72, DeKalb, IL

Built 1987 Load: 37.9 t ADT: 3,600

NORTH STATE ROAD

Poor

Over: DEER CREEK

3310N 1310E, DeKalb, IL

Built 1999 Load: 37.9 t ADT: 1,300

HINCKLEY ROAD

Poor

Over: BATTLE CREEK

1140N 1600F, DeKalb, IL

Built 1977 Load: 38.9 t ADT: 1,100

ELVA RD

Poor

Over: S BR KISHWAUKEE RV

1600N 710E, DeKalb, IL

Built 1961 Load: 44.4 t ADT: 75

Read our methodology - how this data is sourced, computed, and verified.

Related

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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.