County profile · official public datasets

Decatur County, IA

197 public highway bridges tracked in the FHWA National Bridge Inventory: 18.3% rated Good, 41.1% Fair, 40.6% Poor.

197
Public bridges
18.3%
Good condition
40.6%
Poor condition

The verdict

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

Decatur 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.

95th
of 99 on Poor share
40.6%
Poor-condition share
197
public highway bridges
1972
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.

Decatur County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Decatur County ranks #95 of 99 Iowa counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 40.6%). Decatur County, Iowa contains 197 public highway bridges. Roughly 18.3% are rated “Good,” 41.1% “Fair,” and 40.6% “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

197

Public highway bridges in Decatur County

Good condition

18.3%

36 of 197 rated 7-9

Fair condition

41.1%

81 of 197 rated 5-6

Poor condition

40.6%

80 of 197 rated 4 or below

In-state Poor-share rank

#95 of 99

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

Condition distribution

Share of 197 NBI-tracked bridges by lowest applicable component rating.

Good
18.3% (36)
Fair
41.1% (81)
Poor
40.6% (80)

Decatur County's Poor-condition bridges carry 5,581 vehicle crossings a day

That is 4.6% of the county's reported daily bridge traffic on 40.6% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 70 crossings a day against 328 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 197 of 197 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

57.4% of Decatur County's bridges have passed the 50-year mark

113 of the 197 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 18.3% 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 10.9% of the county's Poor-condition bridge traffic

US 69 over ZADIE CREEK, built 1925, carries 610 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 80-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 5,581 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

When Decatur County's bridges were built

197 bridges with a recorded construction year, grouped by decade

bridges

What this shows Construction peaked in the 1960s, when 38 of the county's bridges still in the inventory were built, which is 19.3% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year is 1972, 7 years older than the Iowa average of 1979.

Source FHWA National Bridge Inventory (year built) As of 2024 NBI release

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

The 5 Iowa counties nearest Decatur County in number of bridges, with their condition splits. Its 40.6% Poor share is the 6th-lowest of these 6. Its average build year of 1972 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 Decatur County and the 5 Iowa counties closest to it in inventory size
County Bridges Poor
Dallas County 199 9%
Allamakee County 197 9.1%
Calhoun County 197 25.4%
Decatur County (this page) 197 40.6%
Page County 196 32.1%
Lucas County 195 33.3%

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

Similar inventory size

Nearest county inventories outside IA (197 bridges here).

Similar average build year

Nearest mean year-built outside IA (1972 here).

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

All 197 Good 36 Fair 81 Poor 80

Good-condition bridges (36)

225TH ST

Good

Over: ELK CREEK

068270203, Decatur, IA

Built 2008 Load: 9.8 t ADT: 21

FM

Good

Over: BRUSH CREEK

069251302, Decatur, IA

Built 2006 Load: 13.4 t ADT: 34

275TH ST

Good

Over: STREAM

0682532303, Decatur, IA

Built 2011 Load: 14.0 t ADT: 40

290TH ST

Good

Over: DICKENSON BRANCH

067260305, Decatur, IA

Built 2011 Load: 14.3 t ADT: 5

140TH ST

Good

Over: LITTLE RIVER

070253001, Decatur, IA

Built 2005 Load: 14.4 t ADT: 41

LOCAL

Good

Over: STREAM

069270314, Decatur, IA

Built 2005 Load: 14.5 t ADT: 11

LOCAL

Good

Over: LITTLE RIVER

068251803, Decatur, IA

Built 1999 Load: 16.0 t ADT: 35

LOCAL

Good

Over: STEEL CREEK

068240205, Decatur, IA

Built 1999 Load: 17.4 t ADT: 11

LOCAL

Good

Over: SHORT CREEK

070270204, Decatur, IA

Built 2010 Load: 17.9 t ADT: 26

FM

Good

Over: SHORT CREEK

070271303, Decatur, IA

Built 1994 Load: 17.9 t ADT: 15

LOCAL

Good

Over: STREAM

069271202, Decatur, IA

Built 2003 Load: 18.0 t ADT: 11

LOCAL

Good

Over: WELDON RIVER

068240403, Decatur, IA

Built 1997 Load: 21.0 t ADT: 5

FM

Good

Over: ZADIE CREEK

067272203, Decatur, IA

Built 2003 Load: 22.1 t ADT: 71

IA 2

Good

Over: STREAM

1.0 MI E OF E JCT US 69, Decatur, IA

Built 1927 Load: 22.7 t ADT: 1,720

J 52 280TH ST

Good

Over: DICKENSON BRANCH

067260403, Decatur, IA

Built 2018 Load: 26.7 t ADT: 103

198TH STREET

Good

Over: I-35

1.3 mi. N of Jct. IA 2, Decatur, IA

Built 1969 Load: 30.6 t ADT: 60

PLEASANTON RD

Good

Over: MCGRUDER CREEK

068250406, Decatur, IA

Built 2015 Load: 32.4 t ADT: 329

R15 125TH AVE

Good

Over: GRAND RIVER

070271604, Decatur, IA

Built 2018 Load: 32.4 t ADT: 219

R15 125TH AVE

Good

Over: SAND CREEK

070272110, Decatur, IA

Built 2019 Load: 32.4 t ADT: 219

LOCAL

Good

Over: DICKERSON BRANCH

067260401, Decatur, IA

Built 2000 Load: 32.7 t ADT: 103

FM

Good

Over: WELDON RIVER

068241701, Decatur, IA

Built 2003 Load: 32.7 t ADT: 10

FM

Good

Over: KILGORE CREEK

068253503, Decatur, IA

Built 1986 Load: 33.3 t ADT: 29

215TH ST

Good

Over: MCGRUDER CREEK

069253303, Decatur, IA

Built 2016 Load: 33.3 t ADT: 110

FM

Good

Over: WELDON RIVER

068241602, Decatur, IA

Built 1994 Load: 35.3 t ADT: 34

SB I-35

Good

Over: STREAM

2.0 mi. N of MO St. Line, Decatur, IA

Built 1970 Load: 37.0 t ADT: 7,100

FM

Good

Over: GRAND RIVER

068261708, Decatur, IA

Built 1984 Load: 38.5 t ADT: 20

FM

Good

Over: BRUSH CREEK

068240501, Decatur, IA

Built 2001 Load: 41.5 t ADT: 45

FM

Good

Over: STREAM

070270904, Decatur, IA

Built 2006 Load: 45.7 t ADT: 219

J 66

Good

Over: STREAM

067251812, Decatur, IA

Built 2013 Load: 46.0 t ADT: 329

FM

Good

Over: JONATHAN CREEK

069240601, Decatur, IA

Built 2003 Load: 50.0 t ADT: 421

R30 150TH AVE

Good

Over: EAST FORK BIG CREEK

068273602, Decatur, IA

Built 2017 Load: 50.9 t ADT: 210

LOCAL

Good

Over: STREAM

070273102, Decatur, IA

Built 1996 Load: 51.0 t ADT: 5

FM

Good

Over: BRUSH CREEK

069243104, Decatur, IA

Built 2004 Load: 52.2 t ADT: 40

LOCAL

Good

Over: BEE CREEK

070260301, Decatur, IA

Built 1993 Load: 52.7 t ADT: 20

POPCORN RD

Good

Over: LITTLE RIVER

070251901, Decatur, IA

Built 2016 Load: 55.2 t ADT: 41

R46 PLEASANTON RD

Good

Over: SMALL STREAM

067251004, Decatur, IA

Built 2017 Load: 70.6 t ADT: 110

Read our methodology - how this data is sourced, computed, and verified.

Related

Browse all → | Rankings →
Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainBridges

Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.