County profile · official public datasets

Hardin County, IA

241 public highway bridges tracked in the FHWA National Bridge Inventory: 36.1% rated Good, 36.1% Fair, 27.8% Poor.

241
Public bridges: 36.1%
Good condition: 27.8%
Poor condition

The verdict

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

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

74th
of 99 on Poor share: 27.8%
Poor-condition share: 241
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.

Hardin County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Hardin County ranks #74 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 27.8%). Hardin County, Iowa contains 241 public highway bridges. Roughly 36.1% are rated “Good,” 36.1% “Fair,” and 27.8% “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 Hardin County

Good condition

36.1%

87 of 241 rated 7-9

Fair condition

36.1%

87 of 241 rated 5-6

Poor condition

27.8%

67 of 241 rated 4 or below

In-state Poor-share rank

#74 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

36.1% (87)

Fair

36.1% (87)

Poor

27.8% (67)

Hardin County's Poor-condition bridges carry 12,044 vehicle crossings a day

That is 6.4% of the county's reported daily bridge traffic on 27.8% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 180 crossings a day against 1,582 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 241 of 241 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

26.1% of Hardin County's bridges have passed the 50-year mark

63 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 36.1% 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 15.4% of the county's Poor-condition bridge traffic

MAIN ST over IOWA RIVER, built 1936, carries 1,858 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 67-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 12,044 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

8
1910s

2
1920s

4
1930s

8
1940s

7
1950s

9
1960s

15
1970s

30
1980s

59
1990s

43
2000s

35
2010s

17
2020s

4

What this shows Construction peaked in the 1980s, when 59 of the county's bridges still in the inventory were built, which is 24.5% 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 Iowa average (1979).

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

The 5 Iowa counties nearest Hardin County in number of bridges, with their condition splits. Its 27.8% Poor share is the 4th-lowest of these 6. Its average build year of 1981 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 Hardin 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
Iowa County	241	37.3%	43.6%	19.1%	1980
Hardin County (this page)	241	36.1%	36.1%	27.8%	1981
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 Hardin 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 Hardin 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 (1981 here).

Franklin County, OH · avg 1981 · 922 bridges
Greenville County, SC · avg 1981 · 635 bridges
Montgomery County, OH · avg 1981 · 632 bridges
McLean County, IL · avg 1981 · 624 bridges

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

All 241 Good 87 Fair 87 Poor 67

All bridges (241)

Sort:

Hardin County Bridge Snapshot

Condition distribution

Hardin County's Poor-condition bridges carry 12,044 vehicle crossings a day

26.1% of Hardin County's bridges have passed the 50-year mark

One structure carries 15.4% of the county's Poor-condition bridge traffic

How Hardin 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)

290TH ST

FREMONT ST

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LOCAL

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MILDRED AVE

HIDDEN VALLY DR

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HWY 215

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WASHINGTON ST

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MAIN ST

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HWY 299

HWY 215

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HWY 359

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