County profile · official public datasets

Adair County, IA

306 public highway bridges tracked in the FHWA National Bridge Inventory: 46.7% rated Good, 39.9% Fair, 13.4% Poor.

306
Public bridges: 46.7%
Good condition: 13.4%
Poor condition

The verdict

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

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

Top 28%
lowest Poor share in state: 13.4%
Poor-condition share: 306
public highway bridges: 1983
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.

Adair County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Adair County ranks #28 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 13.4%). Adair County, Iowa contains 306 public highway bridges. Roughly 46.7% are rated “Good,” 39.9% “Fair,” and 13.4% “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

306

Public highway bridges in Adair County

Good condition

46.7%

143 of 306 rated 7-9

Fair condition

39.9%

122 of 306 rated 5-6

Poor condition

13.4%

41 of 306 rated 4 or below

In-state Poor-share rank

#28 of 99

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

Condition distribution

Share of 306 NBI-tracked bridges by lowest applicable component rating.

Good

46.7% (143)

Fair

39.9% (122)

Poor

13.4% (41)

Adair County's Poor-condition bridges carry 1,794 vehicle crossings a day

That is 0.5% of the county's reported daily bridge traffic on 13.4% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 44 crossings a day against 485 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 306 of 306 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

40.5% of Adair County's bridges have passed the 50-year mark

124 of the 306 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 46.7% 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 21.6% of the county's Poor-condition bridge traffic

3RD ST over OVER ABANDON RR, built 1900, carries 387 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 41-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 1,794 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

9
1910s

5
1920s

2
1930s

4
1940s

17
1950s

57
1960s

24
1970s

14
1980s

10
1990s

20
2000s

71
2010s

63
2020s

10

What this shows Construction peaked in the 2000s, when 71 of the county's bridges still in the inventory were built, which is 23.2% of those with a recorded year. That cohort is now 15 to 24 years old in the 2024 inventory. Its average build year (1983) matches the Iowa average (1979).

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

The 5 Iowa counties nearest Adair County in number of bridges, with their condition splits. Its 13.4% Poor share is the 3rd-lowest of these 6. Its average build year of 1983 against a peer-group mean of 1981 is in line with the group.

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

Bridge inventory size and condition shares for Adair County and the 5 Iowa counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Buchanan County	316	42.4%	50.9%	6.6%	1985
Adair County (this page)	306	46.7%	39.9%	13.4%	1983
Marshall County	304	32.9%	23.7%	43.4%	1970
Chickasaw County	302	42.1%	30.1%	27.8%	1986
Cedar County	301	42.9%	37.5%	19.6%	1983
Crawford County	301	42.5%	48.5%	9%	1982

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

Similar inventory size

Nearest county inventories outside IA (306 bridges here).

La Paz County, AZ · 306 bridges
Greene County, PA · 306 bridges
Greene County, TN · 306 bridges
Grant County, WA · 306 bridges

Similar average build year

Nearest mean year-built outside IA (1983 here).

Dallas County, TX · avg 1983 · 3,230 bridges
Bexar County, TX · avg 1983 · 2,342 bridges
Sedgwick County, KS · avg 1983 · 1,333 bridges
Will County, IL · avg 1983 · 649 bridges

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

All 306 Good 143 Fair 122 Poor 41

Good-condition bridges (143)

Sort:

Adair County Bridge Snapshot

Condition distribution

Adair County's Poor-condition bridges carry 1,794 vehicle crossings a day

40.5% of Adair County's bridges have passed the 50-year mark

One structure carries 21.6% of the county's Poor-condition bridge traffic

How Adair 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 (143)

BROWN AVE

TRENTON AVE

LOCAL

300TH ST

ORANGE AVE

LOCAL

MARION AVE

P25 (RIVERSIDE)

180TH ST

ELK AVE

FM

FM

FM

330TH ST

LOCAL

LOCAL

FM

FM

330TH ST

N54 DELTA AVE

G 35 (190TH ST)

PINEWOOD AVE

MARION AVE

QUEBEC AVE

G15 (130TH ST)

220TH ST

MONROE AVE

FM

N77 KENT AVE

FM

280TH ST

LOCAL

E 2ND ST

PINEWOOD AVE

250TH ST

LOCAL

330TH ST

G61 310TH ST

LOCAL

LOCAL

320TH ST

320TH ST

JORDAN AVE

G35 (190TH ST)

N77 KENT AVE

LEWIS AVE

140TH ST

285 ST

LOCAL

FM

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