County profile · official public datasets

Cass County, IA

295 public highway bridges tracked in the FHWA National Bridge Inventory: 25.4% rated Good, 41% Fair, 33.6% Poor.

295
Public bridges: 25.4%
Good condition: 33.6%
Poor condition

The verdict

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

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

90th
of 99 on Poor share: 33.6%
Poor-condition share: 295
public highway bridges: 1976
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.

Cass County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Cass County ranks #90 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 33.6%). Cass County, Iowa contains 295 public highway bridges. Roughly 25.4% are rated “Good,” 41% “Fair,” and 33.6% “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

295

Public highway bridges in Cass County

Good condition

25.4%

75 of 295 rated 7-9

Fair condition

41%

121 of 295 rated 5-6

Poor condition

33.6%

99 of 295 rated 4 or below

In-state Poor-share rank

#90 of 99

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

Condition distribution

Share of 295 NBI-tracked bridges by lowest applicable component rating.

Good

25.4% (75)

Fair

41% (121)

Poor

33.6% (99)

Cass County's Poor-condition bridges carry 7,249 vehicle crossings a day

That is 2% of the county's reported daily bridge traffic on 33.8% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 73 crossings a day against 2,130 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 293 of 295 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

40.7% of Cass County's bridges have passed the 50-year mark

120 of the 295 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 25.4% 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 21% of the county's Poor-condition bridge traffic

FM - OLIVE over NISHNABOTNA RIVER, built 1961, carries 1,524 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 99-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 7,249 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

19
1920s

3
1930s

2
1940s

2
1950s

43
1960s

26
1970s

60
1980s

56
1990s

27
2000s

24
2010s

25
2020s

8

What this shows Construction peaked in the 1970s, when 60 of the county's bridges still in the inventory were built, which is 20.3% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1976) matches the Iowa average (1979).

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

The 5 Iowa counties nearest Cass County in number of bridges, with their condition splits. Its 33.6% Poor share is the 6th-lowest of these 6. Its average build year of 1976 against a peer-group mean of 1979 is in line with the group.

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

Bridge inventory size and condition shares for Cass County and the 5 Iowa counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Cedar County	301	42.9%	37.5%	19.6%	1983
Crawford County	301	42.5%	48.5%	9%	1982
Story County	296	33.1%	53%	13.9%	1968
Cass County (this page)	295	25.4%	41%	33.6%	1976
Delaware County	293	39.2%	53.9%	6.8%	1981
Scott County	291	34.7%	55%	10.3%	1980

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

Similar inventory size

Nearest county inventories outside IA (295 bridges here).

Ottawa County, KS · 295 bridges
Marion County, IL · 296 bridges
Vigo County, IN · 296 bridges
Guadalupe County, TX · 296 bridges

Similar average build year

Nearest mean year-built outside IA (1976 here).

Marion County, IN · avg 1976 · 958 bridges
Mohave County, AZ · avg 1976 · 641 bridges
Comanche County, OK · avg 1976 · 593 bridges
Prince George's County, MD · avg 1976 · 576 bridges

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

All 295 Good 75 Fair 121 Poor 99

Good-condition bridges (75)

Sort:

Cass County Bridge Snapshot

Condition distribution

Cass County's Poor-condition bridges carry 7,249 vehicle crossings a day

40.7% of Cass County's bridges have passed the 50-year mark

One structure carries 21% of the county's Poor-condition bridge traffic

How Cass 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

Good-condition bridges (75)

KINGBIRD AVE

LOCAL

M-56

740TH ST

700TH ST

JASPER RD

FM - 660TH

IA 148

US 71

IA 48

US 71

US 71 & IA 92

IA 92

IA 148

I 80 EB

I 80 WB

EB I-80

YANKTON RD

G53 TUCSON RD

560TH ST

740TH ST

JACKSON RD

LANSING RD

LANSING RD

AKRON RD

G16 BOSTON RD

G 30 WHITE POLE RD

G 30 WHITE POLE RD

WB I-80

FM - JACKSON

JACKSON ST

LAKE ANITA PARK

LOCAL - TROY

LOCAL - 770TH

WB I-80

G43 NEWPORT RD

LOCAL - PELLA

LOCAL - QUIMBY

N28 690TH ST

WB I-80

FM

LOCAL

FM - 710TH

IA 92

I 80 EB

I 80 WB

LOCAL - MEMPHIS

LOCAL/GRT RIVER

INDEPENDENCE RD

LOCAL

Related