County profile · official public datasets

Adams County, IA

186 public highway bridges tracked in the FHWA National Bridge Inventory: 10.2% rated Good, 45.2% Fair, 44.6% Poor.

186
Public bridges: 10.2%
Good condition: 44.6%
Poor condition

The verdict

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

Adams 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.

99th
of 99 on Poor share: 44.6%
Poor-condition share: 186
public highway bridges: 1967
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.

Adams County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Adams County ranks #99 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 44.6%). Adams County, Iowa contains 186 public highway bridges. Roughly 10.2% are rated “Good,” 45.2% “Fair,” and 44.6% “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

186

Public highway bridges in Adams County

Good condition

10.2%

19 of 186 rated 7-9

Fair condition

45.2%

84 of 186 rated 5-6

Poor condition

44.6%

83 of 186 rated 4 or below

In-state Poor-share rank

#99 of 99

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

Condition distribution

Share of 186 NBI-tracked bridges by lowest applicable component rating.

Good

10.2% (19)

Fair

45.2% (84)

Poor

44.6% (83)

Adams County's Poor-condition bridges carry 5,302 vehicle crossings a day

That is 14.2% of the county's reported daily bridge traffic on 44.6% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 64 crossings a day against 584 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 186 of 186 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

71% of Adams County's bridges have passed the 50-year mark

132 of the 186 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 10.2% 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 14.8% of the county's Poor-condition bridge traffic

2ND STREET over DREYS DITCH, built 1920, carries 787 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 83-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 5,302 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

4
1910s

1
1920s

5
1930s

8
1940s

2
1950s

28
1960s

69
1970s

34
1980s

14
1990s

4
2000s

9
2010s

6
2020s

2

What this shows Construction peaked in the 1960s, when 69 of the county's bridges still in the inventory were built, which is 37.1% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year is 1967, 12 years older than the Iowa average of 1979.

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

The 5 Iowa counties nearest Adams County in number of bridges, with their condition splits. Its 44.6% Poor share is the 6th-lowest of these 6. Its average build year of 1967 against a peer-group mean of 1978 is 11 years older.

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

Bridge inventory size and condition shares for Adams County and the 5 Iowa counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Wapello County	190	45.8%	39.5%	14.7%	1987
Adams County (this page)	186	10.2%	45.2%	44.6%	1967
Osceola County	185	38.4%	53%	8.6%	1965
Mills County	184	29.3%	51.6%	19%	1976
Appanoose County	183	41%	27.9%	31.1%	1981
Keokuk County	183	34.4%	45.9%	19.7%	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 Adams 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 Adams County, both outside Iowa so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside IA (186 bridges here).

Fayette County, AL · 186 bridges
Marion County, MO · 186 bridges
Coshocton County, OH · 186 bridges
Montgomery County, TN · 186 bridges

Similar average build year

Nearest mean year-built outside IA (1967 here).

Los Angeles County, CA · avg 1967 · 3,547 bridges
Allegheny County, PA · avg 1967 · 1,294 bridges
Sonoma County, CA · avg 1967 · 609 bridges
Merced County, CA · avg 1967 · 528 bridges

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

All 186 Good 19 Fair 84 Poor 83

All bridges (186)

Sort:

Adams County Bridge Snapshot

Condition distribution

Adams County's Poor-condition bridges carry 5,302 vehicle crossings a day

71% of Adams County's bridges have passed the 50-year mark

One structure carries 14.8% of the county's Poor-condition bridge traffic

How Adams 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 (186)

IA 148

270TH STREET

190TH STREET

190TH STREET

180TH STREET

FM-110TH STREET

OAK AVENUE

WALNUT AVENUE

140TH STREET

190TH STREET

FILBERT AVENUE

FM-150TH STREET

ORANGE AVENUE

250TH STREET

110TH STREET

ORANGE AVENUE

H20 110TH STREET

US 34

265TH STREET

IRONWOOD AVENUE

FM-UNION AVE

WILLOW AVENUE

210TH STREET

CHESTNUT AVENUE

120TH STREET

FILBERT AVENUE

FM-240TH STREET

200TH STREET

230TH STREET

230TH STREET

FM-250TH STREET

REDWOOD AVENUE

POPLAR AVENUE

170TH STREET

140TH STREET

120TH STREET

ASPEN AVENUE

SYCAMORE AVENUE

ADAMS-CASS ST

FM-FILBERT AVE

ORANGE AVENUE

QUINCE AVENUE

265TH STREET

WALNUT AVENUE

QUINCY TRAIL

FM-UNION AVENUE

WILLOW AVENUE

1ST STREET

SYCAMORE AVENUE

UNION AVENUE

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