County profile · official public datasets

Palo Alto County, IA

135 public highway bridges tracked in the FHWA National Bridge Inventory: 23% rated Good, 58.5% Fair, 18.5% Poor.

135
Public bridges: 23%
Good condition: 18.5%
Poor condition

The verdict

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

Palo Alto County pairs a better-than-median Poor-condition share among rated counties in the state with an older average build year than the state inventory.

Top 48%
lowest Poor share in state: 18.5%
Poor-condition share: 135
public highway bridges: 1973
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.

Palo Alto County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Palo Alto County ranks #48 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 18.5%). Palo Alto County, Iowa contains 135 public highway bridges. Roughly 23% are rated “Good,” 58.5% “Fair,” and 18.5% “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

135

Public highway bridges in Palo Alto County

Good condition

23%

31 of 135 rated 7-9

Fair condition

58.5%

79 of 135 rated 5-6

Poor condition

18.5%

25 of 135 rated 4 or below

In-state Poor-share rank

#48 of 99

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

Condition distribution

Share of 135 NBI-tracked bridges by lowest applicable component rating.

Good

23% (31)

Fair

58.5% (79)

Poor

18.5% (25)

Palo Alto County's Poor-condition bridges carry 1,006 vehicle crossings a day

That is 2.6% of the county's reported daily bridge traffic on 18.5% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 40 crossings a day against 586 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 135 of 135 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

43% of Palo Alto County's bridges have passed the 50-year mark

58 of the 135 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 23% 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 11.9% of the county's Poor-condition bridge traffic

FM over SS #98, built 1973, carries 120 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 25-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 1,006 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

pre-1900

1
1910s

7
1920s

9
1930s

4
1940s

2
1950s

7
1960s

15
1970s

32
1980s

20
1990s

18
2000s

14
2010s

5
2020s

1

What this shows Construction peaked in the 1970s, when 32 of the county's bridges still in the inventory were built, which is 23.7% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year is 1973, 6 years older than the Iowa average of 1979.

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

The 5 Iowa counties nearest Palo Alto County in number of bridges, with their condition splits. Its 18.5% Poor share is the 2nd-lowest of these 6. Its average build year of 1973 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 Palo Alto County and the 5 Iowa counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Clay County	151	35.8%	54.3%	9.9%	1982
Muscatine County	144	34.7%	43.8%	21.5%	1979
Hancock County	138	39.9%	39.9%	20.3%	1981
Boone County	135	27.4%	43%	29.6%	1955
Palo Alto County (this page)	135	23%	58.5%	18.5%	1973
Monroe County	130	26.2%	49.2%	24.6%	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 Palo Alto 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 Palo Alto County, both outside Iowa so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside IA (135 bridges here).

Nevada County, CA · 135 bridges
Meriwether County, GA · 135 bridges
Steuben County, IN · 135 bridges
Warren County, IN · 135 bridges

Similar average build year

Nearest mean year-built outside IA (1973 here).

Jefferson County, AL · avg 1973 · 1,068 bridges
Erie County, NY · avg 1973 · 906 bridges
Davidson County, TN · avg 1973 · 832 bridges
Lancaster County, PA · avg 1973 · 801 bridges

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

All 135 Good 31 Fair 79 Poor 25

All bridges (135)

Sort:

Palo Alto County Bridge Snapshot

Condition distribution

Palo Alto County's Poor-condition bridges carry 1,006 vehicle crossings a day

43% of Palo Alto County's bridges have passed the 50-year mark

One structure carries 11.9% of the county's Poor-condition bridge traffic

How Palo Alto 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 (135)

FM

LOCAL

LOCAL

300TH ST

LOCAL

LOCAL

FM

LOCAL

FM

FM

LOCAL RD

LOCAL

FM

FM

FM

LOCAL

LOCAL

FM

FM

LOCAL

LOCAL

LOCAL RD

LOCAL

LOCAL

530TH AVE

FM

LOCAL

FM

LOCAL

IA 4

US 18 & IA 4

FM

LOCAL

FM

FM

LOCAL

LOCAL

LOCAL

FM

B63 (490TH ST)

B55 430TH ST

FM

FM

B63 490TH ST

FM

500TH ST

350TH ST

LOCAL

FM

FM

Related