County profile · official public datasets

Dubuque County, IA

346 public highway bridges tracked in the FHWA National Bridge Inventory: 50.6% rated Good, 40.8% Fair, 8.7% Poor.

346
Public bridges
50.6%
Good condition
8.7%
Poor condition

The verdict

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

Dubuque County pairs a top-quartile lowest Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

Top 13%
lowest Poor share in state
8.7%
Poor-condition share
346
public highway bridges
1989
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.

Dubuque County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Dubuque County ranks #13 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 8.7%). Dubuque County, Iowa contains 346 public highway bridges. Roughly 50.6% are rated “Good,” 40.8% “Fair,” and 8.7% “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

346

Public highway bridges in Dubuque County

Good condition

50.6%

175 of 346 rated 7-9

Fair condition

40.8%

141 of 346 rated 5-6

Poor condition

8.7%

30 of 346 rated 4 or below

In-state Poor-share rank

#13 of 99

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

Condition distribution

Share of 346 NBI-tracked bridges by lowest applicable component rating.

Good
50.6% (175)
Fair
40.8% (141)
Poor
8.7% (30)

Dubuque County's Poor-condition bridges carry 9,093 vehicle crossings a day

That is 1.2% of the county's reported daily bridge traffic on 8.7% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 303 crossings a day against 2,143 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 345 of 346 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

23.1% of Dubuque County's bridges have passed the 50-year mark

80 of the 346 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 50.6% 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 20.6% of the county's Poor-condition bridge traffic

OLD IA 966 over OVER CC RR, built 1936, carries 1,876 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 30-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 9,093 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Dubuque County's bridges were built

346 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 2010s, when 84 of the county's bridges still in the inventory were built, which is 24.3% of those with a recorded year. That cohort is now 5 to 14 years old in the 2024 inventory. Its average build year is 1989, 10 years newer than the Iowa average of 1979.

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

How Dubuque County compares with Iowa's closest counties by inventory size

The 5 Iowa counties nearest Dubuque County in number of bridges, with their condition splits. Its 8.7% Poor share is the 2nd-lowest of these 6. Its average build year of 1989 against a peer-group mean of 1976 is 13 years newer.

Showing the 5 closest of 98 Iowa counties eligible for comparison.

Bridge inventory size and condition shares for Dubuque County and the 5 Iowa counties closest to it in inventory size
County Bridges Poor
Clinton County 372 3%
Johnson County 372 10.2%
Fayette County 362 24.6%
Dubuque County (this page) 346 8.7%
Winneshiek County 342 17.5%
Tama County 337 34.4%

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

Similar inventory size

Nearest county inventories outside IA (346 bridges here).

Similar average build year

Nearest mean year-built outside IA (1989 here).

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

All 346 Good 175 Fair 141 Poor 30

All bridges (346)

NW ARTERIAL NB

Good

Over: WEST 32ND STREET

1.9 mi. S of Jct. IA 3, Dubuque, IA

Built 2002 Load: 44.3 t ADT: 2,947

NW ARTERIAL SB

Good

Over: WEST 32ND STREET

1.9 mi. S of Jct. IA 3, Dubuque, IA

Built 2002 Load: 44.3 t ADT: 3,397

N BANKSTON RD

Good

Over: UNNAMED STREAM

089021203, Dubuque, IA

Built 2022 Load: 46.0 t ADT: 88

NB US 61/151

Good

Over: EAST 9TH ST & CN RR

Over E 9th street, Dubuque, IA

Built 1992 Load: 46.2 t ADT: 11,150

IA 946 SB

Good

Over: VALLEY ST

0.5 mi. S of jct. US 20, Dubuque, IA

Built 1990 Load: 46.2 t ADT: 3,400

HERBER RD

Good

Over: LITTLE MAQUOKETA RIVER

090E22604, Dubuque, IA

Built 2015 Load: 46.3 t ADT: 1,908

SB US 61 RAMP

Good

Over: VACANT LOTS

0.5 Miles N. of Ia. # 3, Dubuque, IA

Built 1991 Load: 46.3 t ADT: 3,820

US 151 SB

Good

Over: N FORK MAQUOKETA RIVER

0.1 mi. N of Jct. IA 136, Dubuque, IA

Built 2002 Load: 47.8 t ADT: 4,550

LOCAL

Good

Over: LYTLE CREEK

087E21704, Dubuque, IA

Built 1997 Load: 48.2 t ADT: 60

SIMON RD

Good

Over: WHITEWATER CREEK

087012502, Dubuque, IA

Built 2021 Load: 48.9 t ADT: 275

MITCHELL MILL RD

Good

Over: SMALL STREAM

088E33204, Dubuque, IA

Built 2017 Load: 51.2 t ADT: 34

LOVERS LANE

Good

Over: CREEK

090E20903, Dubuque, IA

Built 2019 Load: 51.2 t ADT: 45

US 52

Good

Over: FORK GRANGER CREEK

0.9 MI. S OF JCT. US 61, Dubuque, IA

Built 1997 Load: 51.6 t ADT: 7,000

EB US 20

Good

Over: US 52 SB

AT JCT. IA 136, Dubuque, IA

Built 1987 Load: 55.8 t ADT: 3,600

US 52 SB RAMP LOOP

Good

Over: GRANGER CREEK

1.5 MI. S OF DUBUQUE, Dubuque, IA

Built 2019 Load: 66.1 t ADT: 1,770

MONASTARY RD

Good

Over: CATFISH CREEK

000000000, Dubuque, IA

Built 2010 Load: 89.7 t ADT: 1,160

LOCAL

Poor

Over: GRANGER CREEK

088E30611, Dubuque, IA

Built 1925 Load: 0.0 t ADT: 45

LOCAL

Poor

Over: JOHNS CREEK

088023502, Dubuque, IA

Built 1938 Load: 0.0 t ADT: 26

ENTRANCE

Poor

Over: SIDE DITCH BRIDGE

087021601, Dubuque, IA

Built 1912 Load: 0.0 t ADT: 10

LOCAL

Poor

Over: CREEK

090E20905, Dubuque, IA

Built 1925 Load: 8.4 t ADT: 44

CREEK BRANCH LANE

Poor

Over: PRAIRIE CREEK

087E23105, Dubuque, IA

Built 1900 Load: 10.3 t ADT: 11

FM

Poor

Over: CREEK

090021404, Dubuque, IA

Built 1959 Load: 15.9 t ADT: 170

LOCAL

Poor

Over: CREEK

088023004, Dubuque, IA

Built 1928 Load: 17.0 t ADT: 78

LOCAL

Poor

Over: CREEK

087E22904, Dubuque, IA

Built 1940 Load: 17.2 t ADT: 20

LOCAL

Poor

Over: LITTLE MAQUOKETA RIVER

088010304, Dubuque, IA

Built 1952 Load: 17.2 t ADT: 128

LOCAL

Poor

Over: CREEK

087E12704, Dubuque, IA

Built 1936 Load: 17.5 t ADT: 110

LOCAL

Poor

Over: CATFISH CREEK

088E20903, Dubuque, IA

Built 1980 Load: 19.1 t ADT: 530

OLD IA 966

Poor

Over: OVER CC RR

089E13617, Dubuque, IA

Built 1936 Load: 20.9 t ADT: 1,876

FM

Poor

Over: SMALL STREAM

089E12004, Dubuque, IA

Built 1984 Load: 21.4 t ADT: 412

LOCAL

Poor

Over: CREEK

090011303, Dubuque, IA

Built 1940 Load: 21.7 t ADT: 120

LOCAL

Poor

Over: STREAM

087011804, Dubuque, IA

Built 1981 Load: 22.0 t ADT: 90

LOCAL

Poor

Over: CREEK

089023403, Dubuque, IA

Built 1998 Load: 23.0 t ADT: 206

FM

Poor

Over: STREAM

087E22104, Dubuque, IA

Built 1941 Load: 24.0 t ADT: 25

FM

Poor

Over: CREEK

090E12205, Dubuque, IA

Built 1920 Load: 24.0 t ADT: 310

LOCAL

Poor

Over: CREEK

089022404, Dubuque, IA

Built 1971 Load: 26.2 t ADT: 20

3RD AVE SW

Poor

Over: N FORK MAQUOKETA RIVER

3RD AVE SW - N FORK, Dubuque, IA

Built 1967 Load: 27.2 t ADT: 1,651

FISH POND RD

Poor

Over: CREEK

088010304, Dubuque, IA

Built 1997 Load: 30.5 t ADT: 128

FM

Poor

Over: CREEK

088023201, Dubuque, IA

Built 1962 Load: 30.8 t ADT: 490

FM

Poor

Over: CREEK

089010204, Dubuque, IA

Built 1950 Load: 30.8 t ADT: 39

DYERSVILLE EAST RD

Poor

Over: CREEK

089022704, Dubuque, IA

Built 1964 Load: 30.8 t ADT: 511

FM

Poor

Over: LYTLE CREEK

087E20903, Dubuque, IA

Built 1977 Load: 32.4 t ADT: 50

LOCAL

Poor

Over: SOUTH FORK CATFISH CREEK

089E23304, Dubuque, IA

Built 1926 Load: 32.4 t ADT: 756

WILDWOOD DR

Poor

Over: BEE BRANCH

S. OF W. 32ND ST, Dubuque, IA

Built 1970 Load: 32.7 t ADT: 537

LOCAL

Poor

Over: CREEK

087020204, Dubuque, IA

Built 1925 Load: 35.1 t ADT: 30

LOCAL

Poor

Over: CREEK

088022005, Dubuque, IA

Built 1997 Load: 39.8 t ADT: 130

FM

Poor

Over: SMALL

088E13203, Dubuque, IA

Built 1996 Load: 48.2 t ADT: 540

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

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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.