Boone County, IL

111 public highway bridges

Boone County Bridge Snapshot

Boone County, Illinois contains 111 public highway bridges in the FHWA National Bridge Inventory. Roughly 45% are rated “Good,” 31.5% “Fair,” 6.3% “Poor,” and 6.3% are classified as structurally deficient — the federal designation for spans whose deck, superstructure, or substructure has been rated 4 or below on the 0–9 NBI scale. Structurally deficient does not mean unsafe to cross; it means the bridge is on the priority list for repair or replacement.

Inspections in IL are conducted by certified engineers from the state Department of Transportation on a 24-month cycle, and results are reported back to the FHWA each spring. The list below shows every NBI-tracked bridge in the county, sorted by inventory load rating. Use the “Sort by” controls to surface the lowest-rated spans first, and click any row for full inspection history, traffic counts, and condition trends.

Source: FHWA National Bridge Inventory. See methodology for full definitions.

111
Total Bridges
45%
Good
6.3%
Poor
6.3%
Structurally Deficient

Condition Distribution

Good
45% (50)
Fair
31.5% (35)
Poor
6.3% (7)
SD
6.3% (7)

All Bridges (111)

IL 76

Fair

Over: BEAVER CREEK

2.5 MI. S. IL 173, Boone, IL

Built 1990 Load: 51.8 t ADT: 8,250

COUNTY LINE RD

Fair

Over: MUD CREEK

8.0 MI NE BELVIDERE, Boone, IL

Built 1959 Load: 72.9 t ADT: 675

HUNTER ROAD (FAS 3

Fair

Over: BR OF S KINNIKINNICK

0.2 MI E OF CO LINE, Boone, IL

Built 1975 Load: 80.0 t ADT: 2,150

LEROY CENTER RD

Fair

Over: BEAVER CREEK

3.0 MI NW CAPRON, Boone, IL

Built 1968 Load: 88.8 t ADT: 10

FREE CHURCH ROAD

Good

Over: N KINNIKINNICK CREEK

6.5 MI NE ROSCOE, Boone, IL

Built 1973 Load: 18.1 t ADT: 200

GARDEN PRAIRIE RD

Good

Over: SPRING CREEK

3.5 MI S GARDEN PRAI, Boone, IL

Built 1958 Load: 24.3 t ADT: 175

N BOONE SCHOOL RD

Good

Over: S. KINNIKINNICK CRK.

3.0 MI N CALEDONIA, Boone, IL

Built 1965 Load: 24.3 t ADT: 100

N BOONE SCHOOL RD

Good

Over: S. KINNIKINNICK CRK.

3.0 MI N CALEDONIA, Boone, IL

Built 1965 Load: 24.3 t ADT: 100

GRADE SCHOOL ROAD

Good

Over: N KINNIKINNICK CREEK

8.0 MI NW POPLAR GRO, Boone, IL

Built 1973 Load: 24.6 t ADT: 50

WHEELER RD

Good

Over: BRANCH OF KISHWAUKEE

1.5 MI SE CHERRY VAL, Boone, IL

Built 1959 Load: 25.9 t ADT: 1,450

STATE STREET

Good

Over: KISHWAUKEE RIVER

DOWNTOWN BELVIDERE, Boone, IL

Built 2001 Load: 32.4 t ADT: 8,800

ROCKTON RD

Good

Over: N KINNIKINNICK CREEK

6.5 MI NE ROSCOE, Boone, IL

Built 1973 Load: 32.4 t ADT: 250

CRAWFORD ROAD

Good

Over: SPRING CREEK

6.0 MI SE BELVIDERE, Boone, IL

Built 1977 Load: 32.4 t ADT: 250

BELOIT RD

Good

Over: BEAVER CREEK

3.5 MI NW BELVIDERE, Boone, IL

Built 1978 Load: 32.4 t ADT: 3,800

FRUIT FARM ROAD

Good

Over: MOSQUITO CREEK

3.5 MI SE BELVIDERE, Boone, IL

Built 1982 Load: 32.4 t ADT: 25

CARLSON RD

Good

Over: SPRING CREEK

3.0 MI S GARDEN PRAI, Boone, IL

Built 1984 Load: 32.4 t ADT: 325

REEDS CROSSING ROA

Good

Over: MOSQUITO CREEK

4.0 MI SE BELVIDERE, Boone, IL

Built 1983 Load: 32.4 t ADT: 200

GRANGE HALL RD

Good

Over: E BR PISCASAW CR

2.5 M SE POPLAR GROV, Boone, IL

Built 1986 Load: 32.4 t ADT: 50

BLOODS POINT ROAD

Good

Over: CN RR

1.5 MI E WINN CO LN, Boone, IL

Built 1991 Load: 32.4 t ADT: 550

CALEDONIA RD

Good

Over: BEAVER CREEK

2.5 M N. OF BELVIDER, Boone, IL

Built 2003 Load: 32.4 t ADT: 3,350

MARENGO RD (TR 77)

Good

Over: MUD CREEK

1.5 MI N GARDN PRARI, Boone, IL

Built 1994 Load: 32.4 t ADT: 2,000

LAWRENCEVILLE RD

Good

Over: MUD CREEK

1.5MI. NW GARDEN PR., Boone, IL

Built 2000 Load: 32.4 t ADT: 1,400

COUNTY LINE RD

Good

Over: BR PISCASAW CREEK

1.5 MI E OF CAPRON, Boone, IL

Built 2004 Load: 32.4 t ADT: 600

GARDEN PRAIRIE RD

Good

Over: COON CREEK

1.5 MI S GARDEN PR, Boone, IL

Built 2005 Load: 32.4 t ADT: 475

IRENE RD

Good

Over: UNNAMED CREEK

1.5MI S OF US 20, Boone, IL

Built 2007 Load: 32.4 t ADT: 1,650

RIVERSIDE ROAD

Good

Over: BR OF BEAVER CR

3.5MI NE OF BELVIDER, Boone, IL

Built 2007 Load: 32.4 t ADT: 2,350

COUNTY LINE RD

Good

Over: SPRING CREEK

2 MI SE GARDEN PRAIR, Boone, IL

Built 2016 Load: 32.4 t ADT: 100

CENTERVILLE RD

Good

Over: BEAVER CREEK

2 MI W OF CAPRON, Boone, IL

Built 2013 Load: 32.4 t ADT: 150

GARDEN PRAIRIE

Good

Over: KISHWAUKEE RIVER

.5 MI N US 20, Boone, IL

Built 2015 Load: 32.4 t ADT: 2,850

POPLAR GROVE RD

Good

Over: KISHWAUKEE RIVER

NE EDGE OF BELVIDERE, Boone, IL

Built 2020 Load: 32.4 t ADT: 2,200

LIVINGSTON SCHOOL

Good

Over: SOUTH KINNIKINNICK C

3.0 MI N CALEDONIA, Boone, IL

Built 2021 Load: 32.4 t ADT: 50

TOWNLINE RD

Good

Over: BR N KINNINNICK CR

NW CORNER BOONE CO., Boone, IL

Built 1960 Load: 32.4 t ADT: 100

CALEDONIA ROAD

Good

Over: S. KINNIKINNICK CR.

3.3 MI. N. CALEDONIA, Boone, IL

Built 1995 Load: 32.4 t ADT: 1,000

POPLAR GROVE RD

Good

Over: BR. OF BEAVER CREEK

1.75 MI. N. OF IL173, Boone, IL

Built 1998 Load: 32.4 t ADT: 1,350

PEARL STREET RD

Good

Over: KINGSBURY CREEK

AT DEKALB CO. LINE, Boone, IL

Built 1999 Load: 32.4 t ADT: 500

IRENE RD

Good

Over: UNNAMED CRK

0.25 MI S OF US 20, Boone, IL

Built 1900 Load: 32.4 t ADT: 3,200

ORTH ROAD

Good

Over: BR OF BEAVER CREEK

0.6 MI. W. OF IL 76, Boone, IL

Built 2009 Load: 32.4 t ADT: 1,650

TOWN HALL ROAD

Good

Over: UNNAMED STREAM

0.25MI S OF US 20, Boone, IL

Built 2010 Load: 32.4 t ADT: 4,950

FAS-39 (HUNTER RD)

Good

Over: BEAVER CREEK

3.0 MI NW OF CAPRON, Boone, IL

Built 2011 Load: 34.0 t ADT: 1,550

IL 173

Good

Over: BR. BEAVER CREEK

2.7 MI. E. OF IL 76, Boone, IL

Built 2000 Load: 35.0 t ADT: 4,100

IL 173

Good

Over: WILLOW CREEK

0.3 MI E WINN. CO LN, Boone, IL

Built 1994 Load: 42.1 t ADT: 6,250

DENNY RD

Good

Over: GERYLINE CR

3.5 MI SE POPLAR GROVE, Boone, IL

Built 2021 Load: 42.8 t ADT: 300

IL 173

Good

Over: PISCASAW CREEKTRIB.

AT MCHENRY CO. LN., Boone, IL

Built 2001 Load: 45.4 t ADT: 5,000

I 90 WB

Good

Over: MOSQUITO CRK

3 MI SE OF BELVIDERE, Boone, IL

Built 2013 Load: 46.7 t ADT: 27,150

I 90 EB

Good

Over: MOSQUITO CKR

3 MI SE OF BELVIDERE, Boone, IL

Built 2013 Load: 48.9 t ADT: 27,150

BLAINE RD

Good

Over: BEAVER CREEK

3.0 MI NW CAPRON, Boone, IL

Built 2018 Load: 49.6 t ADT: 50

I-90

Good

Over: STREAM

3.8 MI E WINN CO LN, Boone, IL

Built 1958 Load: 50.5 t ADT: 24,800

POPLAR GROVE CREEK

Good

Over: BEAVER CREEK

1.0 MI S POPLAR GR, Boone, IL

Built 2023 Load: 58.3 t ADT: 2,550

I-90

Good

Over: STREAM

0.7 MI W MCHENRY CO, Boone, IL

Built 1958 Load: 67.4 t ADT: 27,150

IL RTE 173

Good

Over: CREEK

.23MI E OF IL 76, Boone, IL

Built 2015 Load: 73.2 t ADT: 4,850

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

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Data sourced from official U.S. government datasets. See our methodology for details. Retrieved and formatted by PlainBridges Editorial