County profile · official public datasets

Allamakee County, IA

197 public highway bridges tracked in the FHWA National Bridge Inventory: 31.5% rated Good, 59.4% Fair, 9.1% Poor.

197
Public bridges: 31.5%
Good condition: 9.1%
Poor condition

The verdict

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

Allamakee County posts a top-quartile lowest Poor-condition share among rated counties in the state across mid-size county bridge inventory.

Top 16%
lowest Poor share in state: 9.1%
Poor-condition share: 197
public highway bridges: 1975
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.

Allamakee County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Allamakee County ranks #16 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 9.1%). Allamakee County, Iowa contains 197 public highway bridges. Roughly 31.5% are rated “Good,” 59.4% “Fair,” and 9.1% “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

197

Public highway bridges in Allamakee County

Good condition

31.5%

62 of 197 rated 7-9

Fair condition

59.4%

117 of 197 rated 5-6

Poor condition

9.1%

18 of 197 rated 4 or below

In-state Poor-share rank

#16 of 99

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

Condition distribution

Share of 197 NBI-tracked bridges by lowest applicable component rating.

Good

31.5% (62)

Fair

59.4% (117)

Poor

9.1% (18)

Allamakee County's Poor-condition bridges carry 4,177 vehicle crossings a day

That is 6.2% of the county's reported daily bridge traffic on 9.1% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 232 crossings a day against 386 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 197 of 197 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

47.7% of Allamakee County's bridges have passed the 50-year mark

94 of the 197 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 31.5% 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 52.7% of the county's Poor-condition bridge traffic

IA 9 over MISSISSIPPI RIVER, built 1931, carries 2,200 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 18-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 4,177 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

8
1910s

3
1920s

5
1930s

5
1940s

4
1950s

32
1960s

32
1970s

21
1980s

14
1990s

20
2000s

30
2010s

15
2020s

8

What this shows Construction peaked in the 1950s, when 32 of the county's bridges still in the inventory were built, which is 16.2% of those with a recorded year. That cohort is now 65 to 74 years old in the 2024 inventory. Its average build year (1975) matches the Iowa average (1979).

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

The 5 Iowa counties nearest Allamakee County in number of bridges, with their condition splits. Its 9.1% Poor share is the 2nd-lowest of these 6. Its average build year of 1975 against a peer-group mean of 1975 is in line with the group.

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

Bridge inventory size and condition shares for Allamakee County and the 5 Iowa counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Dallas County	199	44.7%	46.2%	9%	1978
Calhoun County	197	24.4%	50.3%	25.4%	1971
Decatur County	197	18.3%	41.1%	40.6%	1972
Allamakee County (this page)	197	31.5%	59.4%	9.1%	1975
Page County	196	24%	43.9%	32.1%	1975
Lucas County	195	32.3%	34.4%	33.3%	1977

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

Similar inventory size

Nearest county inventories outside IA (197 bridges here).

Crawford County, IL · 197 bridges
Fountain County, IN · 197 bridges
Warrick County, IN · 197 bridges
Atchison County, KS · 197 bridges

Similar average build year

Nearest mean year-built outside IA (1975 here).

San Bernardino County, CA · avg 1975 · 1,422 bridges
Lane County, OR · avg 1975 · 1,010 bridges
Fulton County, GA · avg 1975 · 775 bridges
Westmoreland County, PA · avg 1975 · 620 bridges

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

All 197 Good 62 Fair 117 Poor 18

Fair-condition bridges (117)

Sort:

Allamakee County Bridge Snapshot

Condition distribution

Allamakee County's Poor-condition bridges carry 4,177 vehicle crossings a day

47.7% of Allamakee County's bridges have passed the 50-year mark

One structure carries 52.7% of the county's Poor-condition bridge traffic

How Allamakee 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

Fair-condition bridges (117)

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