County profile · official public datasets

Iowa County, IA

241 public highway bridges tracked in the FHWA National Bridge Inventory: 37.3% rated Good, 43.6% Fair, 19.1% Poor.

241
Public bridges: 37.3%
Good condition: 19.1%
Poor condition

The verdict

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

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

51st
of 99 on Poor share: 19.1%
Poor-condition share: 241
public highway bridges: 1980
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 #51 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 19.1%). Iowa County, Iowa contains 241 public highway bridges. Roughly 37.3% are rated “Good,” 43.6% “Fair,” and 19.1% “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

241

Public highway bridges in Iowa County

Good condition

37.3%

90 of 241 rated 7-9

Fair condition

43.6%

105 of 241 rated 5-6

Poor condition

19.1%

46 of 241 rated 4 or below

In-state Poor-share rank

#51 of 99

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

Condition distribution

Share of 241 NBI-tracked bridges by lowest applicable component rating.

Good

37.3% (90)

Fair

43.6% (105)

Poor

19.1% (46)

Iowa County's Poor-condition bridges carry 5,155 vehicle crossings a day

That is 1.3% of the county's reported daily bridge traffic on 18.8% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 115 crossings a day against 1,431 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 240 of 241 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

36.9% of Iowa County's bridges have passed the 50-year mark

89 of the 241 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 37.3% 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 45.4% of the county's Poor-condition bridge traffic

M AVE over IOWA RIVER, built 1950, carries 2,340 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 46-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 5,155 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

3
1910s

1
1920s

5
1930s

3
1940s

6
1950s

21
1960s

37
1970s

49
1980s

37
1990s

15
2000s

30
2010s

26
2020s

8

What this shows Construction peaked in the 1970s, when 49 of the county's bridges still in the inventory were built, which is 20.3% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1980) matches the Iowa average (1979).

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

The 5 Iowa counties nearest Iowa County in number of bridges, with their condition splits. Its 19.1% Poor share is the 2nd-lowest of these 6. Its average build year of 1980 against a peer-group mean of 1978 is in line with the group.

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

Bridge inventory size and condition shares for Iowa County and the 5 Iowa counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Cherokee County	248	34.3%	36.7%	29%	1968
Poweshiek County	248	25%	33.1%	41.9%	1974
Jackson County	246	26.4%	56.5%	17.1%	1983
Hardin County	241	36.1%	36.1%	27.8%	1981
Iowa County (this page)	241	37.3%	43.6%	19.1%	1980
Warren County	239	42.7%	36.8%	20.5%	1983

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 Iowa so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside IA (241 bridges here).

Sumter County, AL · 241 bridges
Barber County, KS · 241 bridges
Leavenworth County, KS · 241 bridges
Neosho County, KS · 241 bridges

Similar average build year

Nearest mean year-built outside IA (1980 here).

Tulsa County, OK · avg 1980 · 1,135 bridges
Miami-Dade County, FL · avg 1980 · 1,057 bridges
Pulaski County, AR · avg 1980 · 721 bridges
McLennan County, TX · avg 1980 · 714 bridges

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

All 241 Good 90 Fair 105 Poor 46

All bridges (241)

Sort:

Iowa County Bridge Snapshot

Condition distribution

Iowa County's Poor-condition bridges carry 5,155 vehicle crossings a day

36.9% of Iowa County's bridges have passed the 50-year mark

One structure carries 45.4% of the county's Poor-condition bridge traffic

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

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

All bridges (241)

SS AVE

LOCAL

FM

FM

FM

LOCAL

LOCAL(LWC)

LOCAL

FM

FM

LOCAL

FM

FM W-16

I 80

FM

W 21 (U AVE)

LOCAL

FM

FM

LOCAL

LOCAL

I-80

IA 21

LOCAL

IA 21

EB I-80

US 6

LOCAL

LOCAL

LOCAL

LOCAL

FM

FM

FM

LOCAL

M AVE

FM

FM

FM

FM

FM

US 6

IA 149

US 151

IA 149

IA 220

LOCAL

IA 220

FM

US 151

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