County profile · official public datasets

Des Moines County, IA

176 public highway bridges tracked in the FHWA National Bridge Inventory: 40.9% rated Good, 42.6% Fair, 16.5% Poor.

176
Public bridges: 40.9%
Good condition: 16.5%
Poor condition

The verdict

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

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

Top 37%
lowest Poor share in state: 16.5%
Poor-condition share: 176
public highway bridges: 1978
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.

Des Moines County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Des Moines County ranks #37 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 16.5%). Des Moines County, Iowa contains 176 public highway bridges. Roughly 40.9% are rated “Good,” 42.6% “Fair,” and 16.5% “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

176

Public highway bridges in Des Moines County

Good condition

40.9%

72 of 176 rated 7-9

Fair condition

42.6%

75 of 176 rated 5-6

Poor condition

16.5%

29 of 176 rated 4 or below

In-state Poor-share rank

#37 of 99

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

Condition distribution

Share of 176 NBI-tracked bridges by lowest applicable component rating.

Good

40.9% (72)

Fair

42.6% (75)

Poor

16.5% (29)

Des Moines County's Poor-condition bridges carry 13,279 vehicle crossings a day

That is 4.7% of the county's reported daily bridge traffic on 16.7% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 458 crossings a day against 1,702 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 174 of 176 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

46.6% of Des Moines County's bridges have passed the 50-year mark

82 of the 176 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 40.9% 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 27.9% of the county's Poor-condition bridge traffic

MAIN STREET SOUTH over SMALL CREEK, built 1886, carries 3,705 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 29-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 13,279 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

pre-1900

3
1900s

4
1910s

4
1920s

3
1930s

4
1940s

11
1950s

15
1960s

12
1970s

39
1980s

6
1990s

12
2000s

39
2010s

17
2020s

7

What this shows Construction peaked in the 1970s, when 39 of the county's bridges still in the inventory were built, which is 22.2% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1978) matches the Iowa average (1979).

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

The 5 Iowa counties nearest Des Moines County in number of bridges, with their condition splits. Its 16.5% Poor share is the 1st-lowest of these 6. Its average build year of 1978 against a peer-group mean of 1980 is in line with the group.

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

Bridge inventory size and condition shares for Des Moines County and the 5 Iowa counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Appanoose County	183	41%	27.9%	31.1%	1981
Ida County	182	42.9%	40.7%	16.5%	1983
Wright County	182	35.2%	35.7%	29.1%	1979
Fremont County	179	33%	47.5%	19.6%	1977
Des Moines County (this page)	176	40.9%	42.6%	16.5%	1978
Henry County	173	41%	37.6%	21.4%	1982

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

Similar inventory size

Nearest county inventories outside IA (176 bridges here).

Perry County, KY · 176 bridges
Winston County, MS · 176 bridges
Paulding County, OH · 176 bridges
Spink County, SD · 176 bridges

Similar average build year

Nearest mean year-built outside IA (1978 here).

Orange County, CA · avg 1978 · 1,164 bridges
Sumner County, KS · avg 1978 · 659 bridges
Allen County, IN · avg 1978 · 613 bridges
Livingston County, IL · avg 1978 · 579 bridges

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

All 176 Good 72 Fair 75 Poor 29

All bridges (176)

Sort:

Des Moines County Bridge Snapshot

Condition distribution

Des Moines County's Poor-condition bridges carry 13,279 vehicle crossings a day

46.6% of Des Moines County's bridges have passed the 50-year mark

One structure carries 27.9% of the county's Poor-condition bridge traffic

How Des Moines 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 (176)

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