County profile · official public datasets

Iowa County, WI

209 public highway bridges tracked in the FHWA National Bridge Inventory: 67.5% rated Good, 26.8% Fair, 5.7% Poor.

209
Public bridges: 67.5%
Good condition: 5.7%
Poor condition

The verdict

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

Iowa County pairs a better-than-median Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

Top 46%
lowest Poor share in state: 5.7%
Poor-condition share: 209
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.

Iowa County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Iowa County ranks #33 of 72 Wisconsin counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 5.7%). Iowa County, Wisconsin contains 209 public highway bridges. Roughly 67.5% are rated “Good,” 26.8% “Fair,” and 5.7% “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

209

Public highway bridges in Iowa County

Good condition

67.5%

141 of 209 rated 7-9

Fair condition

26.8%

56 of 209 rated 5-6

Poor condition

5.7%

12 of 209 rated 4 or below

In-state Poor-share rank

#33 of 72

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

Condition distribution

Share of 209 NBI-tracked bridges by lowest applicable component rating.

Good

67.5% (141)

Fair

26.8% (56)

Poor

5.7% (12)

Iowa County's Poor-condition bridges carry 5,117 vehicle crossings a day

That is 2% of the county's reported daily bridge traffic on 5.7% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 426 crossings a day against 934 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 209 of 209 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

16.7% of Iowa County's bridges have passed the 50-year mark

35 of the 209 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 67.5% 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 37.1% of the county's Poor-condition bridge traffic

STH 130-STH 133 over WISCONSIN RIVER 05, built 1942, carries 1,900 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 12-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 5,117 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1920s

2
1930s

9
1940s

8
1950s

4
1960s

7
1970s

17
1980s

52
1990s

28
2000s

53
2010s

21
2020s

8

What this shows Construction peaked in the 2000s, when 53 of the county's bridges still in the inventory were built, which is 25.4% of those with a recorded year. That cohort is now 15 to 24 years old in the 2024 inventory. Its average build year is 1989, 5 years newer than the Wisconsin average of 1984.

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

The 5 Wisconsin counties nearest Iowa County in number of bridges, with their condition splits. Its 5.7% Poor share is the 4th-lowest of these 6. Its average build year of 1989 against a peer-group mean of 1981 is 8 years newer.

Showing the 5 closest of 71 Wisconsin counties eligible for comparison.

Bridge inventory size and condition shares for Iowa County and the 5 Wisconsin counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Jackson County	218	37.2%	55%	7.8%	1975
Lafayette County	217	53.5%	38.2%	8.3%	1978
Dodge County	212	48.1%	47.6%	4.2%	1983
Crawford County	211	56.4%	38.4%	5.2%	1987
Iowa County (this page)	209	67.5%	26.8%	5.7%	1989
Walworth County	206	34.5%	61.7%	3.9%	1981

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

Similar inventory size

Nearest county inventories outside WI (209 bridges here).

McDonough County, IL · 209 bridges
Grant County, LA · 209 bridges
Clinton County, OH · 209 bridges
Fulton County, IL · 210 bridges

Similar average build year

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

Harris County, TX · avg 1989 · 4,029 bridges
Mecklenburg County, NC · avg 1989 · 746 bridges
Buffalo County, NE · avg 1989 · 459 bridges
Brazos County, TX · avg 1989 · 370 bridges

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

All 209 Good 141 Fair 56 Poor 12

Good-condition bridges (141)

Sort:

Iowa County Bridge Snapshot

Condition distribution

Iowa County's Poor-condition bridges carry 5,117 vehicle crossings a day

16.7% of Iowa County's bridges have passed the 50-year mark

One structure carries 37.1% of the county's Poor-condition bridge traffic

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

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

Good-condition bridges (141)

CTH X

LRD SUNNY RIDGE RD

LRD FERNDALE RD

LRD BRENNAN RD

LRD LOST GROVE RD

LRD BURMA RD

LRD SPRING VALLEY

LRD HIGH POINT RD

USH 151 SBL

CTH Y

LRD BIG SPRINGS RD

LRD ROSY LANE

USH 151 NBL

LRD LOWER WYOMING

LRD KORBACK RD

LRD HORSESHOE BEND

LRD BOOTH HOLLOW R

LRD MCKENNA RD

LRD LOWER WYOMING

LRD MORRILL RD

LRD SECTION LINE R

CTH P

LRD PRAIRIE GROVE

LRD LOWER WYOMING

LRD STAR VALLEY RD

LRD LAKEVIEW RD

LRD COON ROCK RD

STH 133

LRD FACTORYROAD

STH 133

STH 133

CTH CH

STH 80

CTH X

LRD MERRY CHRISTMA

LRD CLYDE ROAD

STH 191

STH 191

LRD MILL RD

LRD MT HOPE RD

CTH A

LRD SHOP HILL ROAD

USH 151 SB

CTH W

STH 39

CTH C

CTH H

LRD BLUE RIVER RD

CTH HH

CTH Q

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