County profile · official public datasets

Dickinson County, IA

84 public highway bridges tracked in the FHWA National Bridge Inventory: 40.5% rated Good, 41.7% Fair, 17.9% Poor.

84
Public bridges: 40.5%
Good condition: 17.9%
Poor condition

The verdict

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

Dickinson County posts a better-than-median Poor-condition share among rated counties in the state across rated county bridge inventory.

Top 44%
lowest Poor share in state: 17.9%
Poor-condition share: 84
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.

Dickinson County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Dickinson County ranks #44 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 17.9%). Dickinson County, Iowa contains 84 public highway bridges. Roughly 40.5% are rated “Good,” 41.7% “Fair,” and 17.9% “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

Public highway bridges in Dickinson County

Good condition

40.5%

34 of 84 rated 7-9

Fair condition

41.7%

35 of 84 rated 5-6

Poor condition

17.9%

15 of 84 rated 4 or below

In-state Poor-share rank

#44 of 99

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

Condition distribution

Share of 84 NBI-tracked bridges by lowest applicable component rating.

Good

40.5% (34)

Fair

41.7% (35)

Poor

17.9% (15)

Dickinson County's Poor-condition bridges carry 9,926 vehicle crossings a day

That is 13.3% of the county's reported daily bridge traffic on 18.3% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 662 crossings a day against 1,132 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 82 of 84 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

42.9% of Dickinson County's bridges have passed the 50-year mark

36 of the 84 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 40.5% 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 43.4% of the county's Poor-condition bridge traffic

IA 9 over W FORK LITTLE SIOUX RVR, built 1929, carries 4,310 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 15-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 9,926 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1910s

1
1920s

4
1930s

1
1940s

3
1950s

3
1960s

9
1970s

24
1980s

5
1990s

12
2000s

12
2010s

7
2020s

3

What this shows Construction peaked in the 1970s, when 24 of the county's bridges still in the inventory were built, which is 28.6% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1981) matches the Iowa average (1979).

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

The 5 Iowa counties nearest Dickinson County in number of bridges, with their condition splits. Its 17.9% Poor share is the 4th-lowest of these 6. Its average build year of 1981 against a peer-group mean of 1974 is 7 years newer.

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

Bridge inventory size and condition shares for Dickinson County and the 5 Iowa counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Monroe County	130	26.2%	49.2%	24.6%	1977
Worth County	116	35.3%	48.3%	16.4%	1970
Humboldt County	87	36.8%	52.9%	10.3%	1965
Dickinson County (this page)	84	40.5%	41.7%	17.9%	1981
Emmet County	78	23.1%	60.3%	16.7%	1973
Winnebago County	55	30.9%	36.4%	32.7%	1984

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

Similar inventory size

Nearest county inventories outside IA (84 bridges here).

Chaffee County, CO · 84 bridges
Elbert County, GA · 84 bridges
Glynn County, GA · 84 bridges
Paulding County, GA · 84 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 84 Good 34 Fair 35 Poor 15

All bridges (84)

Sort:

Dickinson County Bridge Snapshot

Condition distribution

Dickinson County's Poor-condition bridges carry 9,926 vehicle crossings a day

42.9% of Dickinson County's bridges have passed the 50-year mark

One structure carries 43.4% of the county's Poor-condition bridge traffic

How Dickinson 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 (84)

LOCAL

LOCAL

LOCAL

LOCAL

LOCAL

FM

IA 9

FM

LOCAL

LOCAL

US 71 & IA 9

LOCAL

N14 (310TH AVE)

LOCAL

LOCAL

LOCAL

FM

LOCAL

FM

SOUTH MARKET ST

330TH AVE

200TH ST

180TH AVE

210TH ST

220TH ST

120TH AVE

LOCAL

FM

FM

HARPEN ST.

FM

LOCAL

FM A-31

FM

240TH AVE

US 71 & IA 9

190TH AVE

US 71

FM

LOCAL

LOCAL

FM

LOCAL

LOCAL

FM

LOCAL

140TH AVE

MINI WAKAN ST PK

TRAPPERS BAY ST PK

LAKESIDE AVE

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