How many bridges are in Iowa?

Iowa has 23,719 public highway bridges tracked in the FHWA National Bridge Inventory. View detailed condition data for each bridge on PlainBridges.

What percentage of bridges in Iowa are in Poor condition?

19.2% of bridge records in Iowa are in Poor condition, meaning the lowest applicable major-component rating is 4 or below, compared with 7.5% across state inventories.

State profile · Above median Poor share

Iowa bridge safety

Name: Iowa public highway bridge inventory (FHWA NBI)
Creator: PlainBridges
License: https://creativecommons.org/publicdomain/zero/1.0/

According to the Federal Highway Administration's 2024 National Bridge Inventory, condition ratings, load ratings, and Poor-condition shares for every public highway bridge in Iowa.

Compiled by PlainBridges

23,719
Public bridges: 38.8%
Good condition: 19.2%
Poor condition

Iowa holds 23,719 public highway bridges (#7 of 52 by inventory) with a 19.16% Poor share (#1 of 52 by Poor share).

That is 19.2% of the state's inventory, against an average of 7.5% across the 54 states and territories with Poor-rated bridges on file, which places it 53 of 54 ordered from the lowest Poor share upward. A bridge is rated Poor when its weakest applicable component scores 4 or below on the inspecting agency's 0-9 scale, so the category is a maintenance and funding signal rather than a closure order or a live crossing-safety verdict.

Inventory: FHWA NBI 2024 · last ETL August 2026

Total Bridges

23,719

Public highway bridges in Iowa

Good Condition

38.8%

9,213 bridges rated 7-9

-11.2pp vs 50% benchmark

Poor Condition

19.2%

4,544 bridges whose lowest applicable component is rated 0-4

11.6pp vs national avg 7.5%

Iowa vs national bridge condition

Iowa - Good condition share 38.8%

National avg

Share of bridges rated 7-9 on the FHWA 0-9 scale (deck, superstructure, substructure all good).

Iowa - Poor-condition share 63.9%

National avg

Lower is better. Bar maxes at 30% (worst-state ceiling). National average sits at 7.5%.

Inventory size and Poor-condition share are different measures: Iowa has 23,719 bridges and a 19.2% Poor-condition share in the 2024 NBI, rank #53 of 54 jurisdictions ordered from the lowest share upward. The dashed comparisons mark the national average state rate and the midpoint of the plotted inventory range; neither is a live safety or closure threshold.

Iowa vs all states by public bridge inventory

Where this state's FHWA NBI public-highway bridge count sits among every state and territory on PlainBridges

23,719 7th of 54 higher than 47 of 54 states

States and territories, banded by public bridge inventory size

Each bar is a band; taller bars hold more states. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.

Source FHWA National Bridge Inventory · 2024

Read the rank neighborhood for Iowa

The highlighted point is Iowa: 23,719 bridges and 19.16% in Poor condition, rank #53 of 54 jurisdictions ordered from the lowest share upward. The five jurisdictions immediately above and below Iowa on that same Poor-share ordering:

South Dakota: 5,887 bridges · 16.36% Poor
West Virginia: 7,348 bridges · 18.64% Poor
Iowa: 23,719 bridges · 19.16% Poor
Virgin Islands: 24 bridges · 29.17% Poor

The full national sortable table lives on the rankings page.

Material families in Iowa

Exclusive FHWA material families across all 23,719 bridges in this state; continuous variants fold into the parent family. Orthogonal to the Poor-share scatter above.

Concrete 10,112 bridges (43%) Prestressed concrete 5,075 bridges (21%) Steel 7,166 bridges (30%) Wood or timber 1,336 bridges (6%) Other 30 bridges (0%)

Who maintains Iowa’s inventory

State agency holds 17.7% of the 23,719 public highway bridges filed under Iowa in the 2024 NBI, the agency-of-record split for this state, not a condition verdict.

State agency 4,204 bridges (18%) County agency 18,221 bridges (77%) Local agency 1,259 bridges (5%) Federal agency 32 bridges (0%) Other 3 bridges (0%)

When Iowa’s bridges were built

Pre-1950 construction accounts for 12.4% of the 23,719 bridges with a recorded original year in Iowa. Era bands are orthogonal to the Poor-share ranking above.

Pre-1950 2,932 bridges (12%) 1950–1979 8,797 bridges (37%) 1980–1999 5,692 bridges (24%) 2000+ 6,298 bridges (27%)

Condition Distribution

Bridge inventory deck-condition mix - Iowa (FHWA NBI)

Counties (99)

Adair 306 Adams 186 Allamakee 197 Appanoose 183 Audubon 206 Benton 374 Black Hawk 489 Boone 135 Bremer 266 Buchanan 316 Buena Vista 156 Butler 289 Calhoun 197 Carroll 249 Cass 295 Cedar 301 Cerro Gordo 266 Cherokee 248 Chickasaw 302 Clarke 168 Clay 151 Clayton 256 Clinton 372 Crawford 301 Dallas 199 Davis 165 Decatur 197 Delaware 293 Des Moines 176 Dickinson 84 Dubuque 346 Emmet 78 Fayette 362 Floyd 213 Franklin 228 Fremont 179 Greene 168 Grundy 289 Guthrie 263 Hamilton 165 Hancock 138 Hardin 241 Harrison 217 Henry 173 Howard 210 Humboldt 87 Ida 182 Iowa 241 Jackson 246 Jasper 382 Jefferson 157 Johnson 372 Jones 231 Keokuk 183 Kossuth 267 Lee 214 Linn 506 Louisa 151 Lucas 195 Lyon 276 Madison 225 Mahaska 225 Marion 217 Marshall 304 Mills 184 Mitchell 167 Monona 162 Monroe 130 Montgomery 210 Muscatine 144 O'Brien 264 Osceola 185 Page 196 Palo Alto 135 Plymouth 432 Pocahontas 201 Polk 545 Pottawattamie 557 Poweshiek 248 Ringgold 217 Sac 224 Scott 291 Shelby 207 Sioux 449 Story 296 Tama 337 Taylor 220 Union 169 Van Buren 156 Wapello 190 Warren 239 Washington 207 Wayne 163 Webster 190 Winnebago 55 Winneshiek 342 Woodbury 455 Worth 116 Wright 182

Iowa vs nearby ranks

Adjacent states by Poor-condition share (lower share = better)

States are ranked by the share of bridges whose lowest applicable component rating is 4 or below. This describes recorded condition; it does not measure funding effectiveness or live crossing safety. States here sit immediately above and below Iowa on the same metric.

South Dakota

16.36% top marginal rate

Structure: Progressive
Burden @ $100K: $5,887

West Virginia

18.64% top marginal rate

Structure: Progressive
Burden @ $100K: $7,348

Selected

Iowa

19.16% top marginal rate

Structure: Progressive
Burden @ $100K: $23,719

Virgin Islands

29.17% top marginal rate

Structure: Progressive
Burden @ $100K: $24

Bridges Needing Most Attention in Iowa

Six lowest-condition bridges in Iowa, ranked by the portal's composite display score. Inspection intervals are risk-based under current NBIS rules.

MAIN ST

Poor

Over: IOWA RIVER

089211800, Hardin, IA

Built 1936 Load: 0.0 t ADT: 1,858

SO MAIN ST

Poor

Over: CASCADE LANDING

000000000, Des Moines, IA

Built 1896 Load: 0.0 t ADT: 743

E 13TH ST

Poor

Over: OVER I.C.E. RR

000000000, Scott, IA

Built 1900 Load: 0.0 t ADT: 358

EMERSON ST

Poor

Over: DRAINAGE

000000000, Madison, IA

Built 1965 Load: 0.0 t ADT: 396

1ST AVE S

Poor

Over: 21ST ST & RR

089282000, Webster, IA

Built 1968 Load: 0.0 t ADT: 9,860

1ST ST

Poor

Over: DRAINAGE

D60500515, Audubon, IA

Built 1930 Load: 0.0 t ADT: 9

All Bridges in Iowa

Sort by:

Iowa vs national bridge condition

Material families in Iowa

Who maintains Iowa’s inventory

When Iowa’s bridges were built

Condition Distribution

Counties (99)

Bridges Needing Most Attention in Iowa

MAIN ST

SO MAIN ST

E 13TH ST

EMERSON ST

1ST AVE S

1ST ST

All Bridges in Iowa

FM

FM

FM

LOCAL RD

FM

W60 OLD STAGE RD

LOCAL RD

FM

LOCAL

LOCAL

FM

LOCAL

FM

LOCAL

160TH ST

C13

LOCAL

LOCAL

FM

LOCAL - A AVE

IOWA AVE

FANTAIL RD

OSTERDOCK RD

HAZEL RD

FORT RD

BUSH RD

HARBER RD

CHARIOT RD

BIRCH RD

KEYSTONE RD

KEYSTONE RD

KING RD

APPLE RD

CHARIOT RD

ABBEY RD

DOGWOOD AVE

ASPEN AVE

CONCORD AVE

LOCAL

I AVE

LOCAL

LOCAL 180TH AVE

FM 110TH AVE

FM 280 AVE

FM 300 AVE

LOCAL

LOCAL

FM

LOCAL

LOCAL

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