County profile · official public datasets

Buchanan County, IA

316 public highway bridges tracked in the FHWA National Bridge Inventory: 42.4% rated Good, 50.9% Fair, 6.6% Poor.

316
Public bridges: 42.4%
Good condition: 6.6%
Poor condition

The verdict

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

Buchanan County pairs a top-10% lowest Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

Top 9%
lowest Poor share in state: 6.6%
Poor-condition share: 316
public highway bridges: 1985
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.

Buchanan County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Buchanan County ranks #9 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 6.6%). Buchanan County, Iowa contains 316 public highway bridges. Roughly 42.4% are rated “Good,” 50.9% “Fair,” and 6.6% “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

316

Public highway bridges in Buchanan County

Good condition

42.4%

134 of 316 rated 7-9

Fair condition

50.9%

161 of 316 rated 5-6

Poor condition

6.6%

21 of 316 rated 4 or below

In-state Poor-share rank

#9 of 99

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

Condition distribution

Share of 316 NBI-tracked bridges by lowest applicable component rating.

Good

42.4% (134)

Fair

50.9% (161)

Poor

6.6% (21)

Buchanan County's Poor-condition bridges carry 10,438 vehicle crossings a day

That is 3.3% of the county's reported daily bridge traffic on 6.6% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 497 crossings a day against 1,087 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 316 of 316 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

34.5% of Buchanan County's bridges have passed the 50-year mark

109 of the 316 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 42.4% 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 25.6% of the county's Poor-condition bridge traffic

RACINE AVE over DRAINAGE DITCH, built 1953, carries 2,671 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 21-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 10,438 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

2
1910s

2
1920s

4
1940s

5
1950s

42
1960s

41
1970s

35
1980s

42
1990s

25
2000s

59
2010s

55
2020s

4

What this shows Construction peaked in the 2000s, when 59 of the county's bridges still in the inventory were built, which is 18.7% of those with a recorded year. That cohort is now 15 to 24 years old in the 2024 inventory. Its average build year is 1985, 6 years newer than the Iowa average of 1979.

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

The 5 Iowa counties nearest Buchanan County in number of bridges, with their condition splits. Its 6.6% Poor share is the 1st-lowest of these 6. Its average build year of 1985 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 Buchanan County and the 5 Iowa counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Buchanan County (this page)	316	42.4%	50.9%	6.6%	1985
Adair County	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 Buchanan 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 Buchanan County, both outside Iowa so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside IA (316 bridges here).

Jefferson County, NY · 316 bridges
Cleveland County, OK · 316 bridges
Gwinnett County, GA · 317 bridges
Cherokee County, KS · 317 bridges

Similar average build year

Nearest mean year-built outside IA (1985 here).

Hillsborough County, FL · avg 1985 · 840 bridges
Lancaster County, NE · avg 1985 · 661 bridges
Nueces County, TX · avg 1985 · 528 bridges
Grayson County, TX · avg 1985 · 513 bridges

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

All 316 Good 134 Fair 161 Poor 21

Fair-condition bridges (161)

Sort:

Buchanan County Bridge Snapshot

Condition distribution

Buchanan County's Poor-condition bridges carry 10,438 vehicle crossings a day

34.5% of Buchanan County's bridges have passed the 50-year mark

One structure carries 25.6% of the county's Poor-condition bridge traffic

How Buchanan 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

Fair-condition bridges (161)

FM

FM

POSTEL AVE

FM

220TH ST

LOCAL 240TH ST

WB US 20

US 20

FM 310TH ST

IOWA AVE

LOC UNION AVE

FM

FM

LOC 110TH ST

LOCAL 240TH ST

330TH ST

3RD ST NE

IA 150

280TH ST

LOCAL

LOCAL 310TH ST.

LOCAL

FM

FM 140TH ST

EB US 20

IA 150

FM

FM 150TH ST

FM

FM

IA 187

JACKSON AVE

WB US 20

FM

KEOKUK AVE

IA 150

LOCAL FROST AVE

FM DENISON AVE

LOCAL

FM W45

FM

FM

FM W-45

FM

FM QUONSET AVE

FM 140TH ST

FM 155TH ST

2ND ST NE

FM

FM 250TH ST

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