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.

When Palo Alto County's bridges were built

135 bridges with a recorded construction year, grouped by decade

bridges

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.

Source FHWA National Bridge Inventory (year built) As of 2024 NBI release

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 Poor
Clay County 151 9.9%
Muscatine County 144 21.5%
Hancock County 138 20.3%
Boone County 135 29.6%
Palo Alto County (this page) 135 18.5%
Monroe County 130 24.6%

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).

Similar average build year

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

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

Good-condition bridges (31)

IA 4

Good

Over: DRAINAGE DITCH

3.0 mi. N of N jct. US 18, Palo Alto, IA

Built 1976 Load: 21.7 t ADT: 2,010

US 18 & IA 4

Good

Over: W FORK DES MOINES RIVER

2.5 mi E of W jct IA 4, Palo Alto, IA

Built 1965 Load: 22.1 t ADT: 4,890

FM

Good

Over: SILVER CREEK

095342306, Palo Alto, IA

Built 2002 Load: 27.3 t ADT: 769

LOCAL

Good

Over: DD 81

094312903, Palo Alto, IA

Built 1996 Load: 34.6 t ADT: 72

FM

Good

Over: DD 81

094311705, Palo Alto, IA

Built 1994 Load: 35.3 t ADT: 669

FM

Good

Over: DES MOINES RIVER

095312908, Palo Alto, IA

Built 1996 Load: 35.3 t ADT: 290

LOCAL

Good

Over: STREAM

094313302, Palo Alto, IA

Built 1989 Load: 37.1 t ADT: 11

LOCAL

Good

Over: CYLINDER CREEK

096311901, Palo Alto, IA

Built 1992 Load: 37.1 t ADT: 31

LOCAL

Good

Over: JACK CREEK

097320604, Palo Alto, IA

Built 1990 Load: 37.1 t ADT: 26

FM

Good

Over: OLD CHANNEL DES MOINES R

094311603, Palo Alto, IA

Built 1994 Load: 38.2 t ADT: 669

B63 (490TH ST)

Good

Over: DD 63

094332901, Palo Alto, IA

Built 2014 Load: 38.6 t ADT: 309

B55 430TH ST

Good

Over: DD #61

095312601, Palo Alto, IA

Built 2016 Load: 38.6 t ADT: 478

FM

Good

Over: DES MOINES RIVER

095312908, Palo Alto, IA

Built 1996 Load: 39.5 t ADT: 290

FM

Good

Over: JACK CREEK

097331201, Palo Alto, IA

Built 2007 Load: 40.0 t ADT: 888

B63 490TH ST

Good

Over: DD84

094342601, Palo Alto, IA

Built 2021 Load: 40.2 t ADT: 309

FM

Good

Over: DES MOINES RIVER

094310803, Palo Alto, IA

Built 1988 Load: 41.1 t ADT: 46

500TH ST

Good

Over: STREAM

094313201, Palo Alto, IA

Built 2016 Load: 43.1 t ADT: 5

350TH ST

Good

Over: STREAM

096331501, Palo Alto, IA

Built 2016 Load: 43.1 t ADT: 26

LOCAL

Good

Over: PRAIRIE CREEK

094312403, Palo Alto, IA

Built 1990 Load: 45.4 t ADT: 73

FM

Good

Over: DD 84

094342302, Palo Alto, IA

Built 2002 Load: 45.4 t ADT: 1,008

FM

Good

Over: PRAIRIE CREEK

094311303, Palo Alto, IA

Built 2005 Load: 45.7 t ADT: 681

FM

Good

Over: DD #48

094322601, Palo Alto, IA

Built 2005 Load: 45.7 t ADT: 669

FM

Good

Over: DD 98

094323005, Palo Alto, IA

Built 2005 Load: 45.7 t ADT: 709

FM

Good

Over: DD 63

094330801, Palo Alto, IA

Built 1995 Load: 45.7 t ADT: 34

270 ST

Good

Over: DD 63

094331803, Palo Alto, IA

Built 2000 Load: 45.7 t ADT: 21

FM

Good

Over: DD 84

094342601, Palo Alto, IA

Built 2006 Load: 45.7 t ADT: 309

FM

Good

Over: DD 84

094342601, Palo Alto, IA

Built 2006 Load: 45.7 t ADT: 309

LOCAL

Good

Over: DD 61

095312301, Palo Alto, IA

Built 1997 Load: 45.7 t ADT: 15

LOCAL

Good

Over: STREAM

095322806, Palo Alto, IA

Built 1998 Load: 45.7 t ADT: 11

FM

Good

Over: SILVER CREEK

095342401, Palo Alto, IA

Built 2006 Load: 45.7 t ADT: 538

IA 4

Good

Over: DITCH #49

5.2 MI. N. OF JCT. US 18, Palo Alto, IA

Built 2018 Load: 56.1 t ADT: 2,010

Read our methodology - how this data is sourced, computed, and verified.

Related

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Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainBridges

Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.