County profile · official public datasets

Sac County, IA

224 public highway bridges tracked in the FHWA National Bridge Inventory: 35.7% rated Good, 30.8% Fair, 33.5% Poor.

224
Public bridges: 35.7%
Good condition: 33.5%
Poor condition

The verdict

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

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

89th
of 99 on Poor share: 33.5%
Poor-condition share: 224
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.

Sac County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Sac County ranks #89 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 33.5%). Sac County, Iowa contains 224 public highway bridges. Roughly 35.7% are rated “Good,” 30.8% “Fair,” and 33.5% “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

224

Public highway bridges in Sac County

Good condition

35.7%

80 of 224 rated 7-9

Fair condition

30.8%

69 of 224 rated 5-6

Poor condition

33.5%

75 of 224 rated 4 or below

In-state Poor-share rank

#89 of 99

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

Condition distribution

Share of 224 NBI-tracked bridges by lowest applicable component rating.

Good

35.7% (80)

Fair

30.8% (69)

Poor

33.5% (75)

Sac County's Poor-condition bridges carry 8,185 vehicle crossings a day

That is 9.7% of the county's reported daily bridge traffic on 33.6% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 109 crossings a day against 701 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 223 of 224 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

47.8% of Sac County's bridges have passed the 50-year mark

107 of the 224 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 35.7% 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 13.6% of the county's Poor-condition bridge traffic

NEEDHAM AVE over SMALL NATURAL STREAM, built 1939, carries 1,117 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 75-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 8,185 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

2
1910s

12
1920s

20
1930s

15
1940s

2
1950s

19
1960s

22
1970s

27
1980s

30
1990s

19
2000s

21
2010s

29
2020s

6

What this shows Construction peaked in the 1980s, when 30 of the county's bridges still in the inventory were built, which is 13.4% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year is 1973, 6 years older than the Iowa average of 1979.

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

The 5 Iowa counties nearest Sac County in number of bridges, with their condition splits. Its 33.5% Poor share is the 4th-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 Sac County and the 5 Iowa counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Jones County	231	36.8%	58.9%	4.3%	1981
Franklin County	228	44.7%	42.1%	13.2%	1982
Madison County	225	16%	46.7%	37.3%	1968
Mahaska County	225	28.4%	39.1%	32.4%	1972
Sac County (this page)	224	35.7%	30.8%	33.5%	1973
Taylor County	220	24.5%	37.7%	37.7%	1973

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

Similar inventory size

Nearest county inventories outside IA (224 bridges here).

Conecuh County, AL · 224 bridges
Riley County, KS · 224 bridges
Clarke County, MS · 224 bridges
Sullivan County, MO · 224 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 224 Good 80 Fair 69 Poor 75

Poor-condition bridges (75)

Sort:

Sac County Bridge Snapshot

Condition distribution

Sac County's Poor-condition bridges carry 8,185 vehicle crossings a day

47.8% of Sac County's bridges have passed the 50-year mark

One structure carries 13.6% of the county's Poor-condition bridge traffic

How Sac 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

Poor-condition bridges (75)

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