State profile · Below median Poor share

Idaho bridge safety

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 Idaho.

4,616
Public bridges
29.5%
Good condition
4.9%
Poor condition

Idaho holds 4,616 public highway bridges (#37 of 52 by inventory) with a 4.9% Poor share (#33 of 52 by Poor share).

That is 4.9% 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 20 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

4,616

Public highway bridges in Idaho

Good Condition

29.5%

1,363 bridges rated 7-9

-20.5pp vs 50% benchmark

Poor Condition

4.9%

226 bridges whose lowest applicable component is rated 0-4

-2.6pp vs national avg 7.5%

Idaho vs national bridge condition

Idaho - Good condition share 29.5%
National avg

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

Idaho - Poor-condition share 16.3%
National avg

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

Idaho in the national condition pattern

Each point is a state or territory in the FHWA NBI; the highlighted point is this profile.

Inventory size and Poor-condition share are different measures: Idaho has 4,616 bridges and a 4.9% Poor-condition share in the 2024 NBI, rank #20 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. Scatter plot of 54 data points. 0%10%20%30%40% 0k20k40k60k Public bridges in inventory (thousands) Poor-condition share (%) ID, Public bridges in inventory (thousands): 4.6k · Poor-condition share (%): 4.9%AL, Public bridges in inventory (thousands): 16.2k · Poor-condition share (%): 3.35%AK, Public bridges in inventory (thousands): 1.7k · Poor-condition share (%): 7.89%AZ, Public bridges in inventory (thousands): 8.6k · Poor-condition share (%): 1.15%AR, Public bridges in inventory (thousands): 13k · Poor-condition share (%): 5.43%CA, Public bridges in inventory (thousands): 25.8k · Poor-condition share (%): 5.91%CO, Public bridges in inventory (thousands): 9k · Poor-condition share (%): 4.82%CT, Public bridges in inventory (thousands): 4.4k · Poor-condition share (%): 4.72%DE, Public bridges in inventory (thousands): 0.9k · Poor-condition share (%): 1.26%DC, Public bridges in inventory (thousands): 0.3k · Poor-condition share (%): 1.95%FL, Public bridges in inventory (thousands): 13k · Poor-condition share (%): 2.79%GA, Public bridges in inventory (thousands): 15.1k · Poor-condition share (%): 1.59%GU, Public bridges in inventory (thousands): 0k · Poor-condition share (%): 12.77%HI, Public bridges in inventory (thousands): 1.2k · Poor-condition share (%): 6.53%IL, Public bridges in inventory (thousands): 26.9k · Poor-condition share (%): 9.35%IN, Public bridges in inventory (thousands): 19.5k · Poor-condition share (%): 5.22%IA, Public bridges in inventory (thousands): 23.7k · Poor-condition share (%): 19.16%KS, Public bridges in inventory (thousands): 24.9k · Poor-condition share (%): 5.26%KY, Public bridges in inventory (thousands): 14.5k · Poor-condition share (%): 7.37%LA, Public bridges in inventory (thousands): 12.7k · Poor-condition share (%): 11.48%ME, Public bridges in inventory (thousands): 2.5k · Poor-condition share (%): 15.41%MD, Public bridges in inventory (thousands): 5.5k · Poor-condition share (%): 4.56%MA, Public bridges in inventory (thousands): 5.3k · Poor-condition share (%): 8.88%MI, Public bridges in inventory (thousands): 11.4k · Poor-condition share (%): 11.27%MN, Public bridges in inventory (thousands): 13.5k · Poor-condition share (%): 4.44%MS, Public bridges in inventory (thousands): 16.7k · Poor-condition share (%): 6.03%MO, Public bridges in inventory (thousands): 24.6k · Poor-condition share (%): 8.95%MT, Public bridges in inventory (thousands): 5.2k · Poor-condition share (%): 6.81%NE, Public bridges in inventory (thousands): 15.4k · Poor-condition share (%): 7.9%NV, Public bridges in inventory (thousands): 2.1k · Poor-condition share (%): 1.14%NH, Public bridges in inventory (thousands): 2.5k · Poor-condition share (%): 7.51%NJ, Public bridges in inventory (thousands): 6.8k · Poor-condition share (%): 6.01%NM, Public bridges in inventory (thousands): 4k · Poor-condition share (%): 4.51%NY, Public bridges in inventory (thousands): 17.6k · Poor-condition share (%): 9.43%NC, Public bridges in inventory (thousands): 19.2k · Poor-condition share (%): 6.76%ND, Public bridges in inventory (thousands): 4.3k · Poor-condition share (%): 10.98%OH, Public bridges in inventory (thousands): 26.7k · Poor-condition share (%): 4.74%OK, Public bridges in inventory (thousands): 22.9k · Poor-condition share (%): 7.7%OR, Public bridges in inventory (thousands): 8.3k · Poor-condition share (%): 4.61%PA, Public bridges in inventory (thousands): 23.3k · Poor-condition share (%): 12.58%PR, Public bridges in inventory (thousands): 2.4k · Poor-condition share (%): 13.92%RI, Public bridges in inventory (thousands): 0.8k · Poor-condition share (%): 15.2%SC, Public bridges in inventory (thousands): 9.5k · Poor-condition share (%): 6.17%SD, Public bridges in inventory (thousands): 5.9k · Poor-condition share (%): 16.36%TN, Public bridges in inventory (thousands): 20.4k · Poor-condition share (%): 4.41%TX, Public bridges in inventory (thousands): 56.7k · Poor-condition share (%): 1.23%UT, Public bridges in inventory (thousands): 3.1k · Poor-condition share (%): 2.91%VT, Public bridges in inventory (thousands): 2.9k · Poor-condition share (%): 2.9%VI, Public bridges in inventory (thousands): 0k · Poor-condition share (%): 29.17%VA, Public bridges in inventory (thousands): 14.1k · Poor-condition share (%): 3.39%WA, Public bridges in inventory (thousands): 8.5k · Poor-condition share (%): 5.45%WV, Public bridges in inventory (thousands): 7.3k · Poor-condition share (%): 18.64%WI, Public bridges in inventory (thousands): 14.4k · Poor-condition share (%): 6.52%WY, Public bridges in inventory (thousands): 3.1k · Poor-condition share (%): 6.51%
Inventory size and Poor-condition share are different measures: Idaho has 4,616 bridges and a 4.9% Poor-condition share in the 2024 NBI, rank #20 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.

Idaho 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

4,616 37th of 54 higher than 17 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 Idaho

The highlighted point is Idaho: 4,616 bridges and 4.90% in Poor condition, rank #20 of 54 jurisdictions ordered from the lowest share upward. The five jurisdictions immediately above and below Idaho on that same Poor-share ordering:

  • Ohio: 26,729 bridges · 4.74% Poor
  • Colorado: 8,965 bridges · 4.82% Poor
  • Idaho: 4,616 bridges · 4.90% Poor
  • Indiana: 19,495 bridges · 5.22% Poor
  • Kansas: 24,894 bridges · 5.26% Poor

The full national sortable table lives on the rankings page.

Material families in Idaho

Exclusive FHWA material families across all 4,616 bridges in this state; continuous variants fold into the parent family. Orthogonal to the Poor-share scatter above.

Who maintains Idaho’s inventory

State agency holds 29.8% of the 4,616 public highway bridges filed under Idaho in the 2024 NBI, the agency-of-record split for this state, not a condition verdict.

When Idaho’s bridges were built

Pre-1950 construction accounts for 7.0% of the 4,616 bridges with a recorded original year in Idaho. Era bands are orthogonal to the Poor-share ranking above.

Condition Distribution

Idaho29.5%65.6%GoodFairPoor
Bridge inventory deck-condition mix - Idaho (FHWA NBI)

Counties (44)

Ada 299 Adams 87 Bannock 124 Bear Lake 34 Benewah 47 Bingham 263 Blaine 96 Boise 88 Bonner 104 Bonneville 213 Boundary 83 Butte 32 Camas 61 Canyon 292 Caribou 45 Cassia 116 Clark 40 Clearwater 88 Custer 128 Elmore 97 Franklin 23 Fremont 137 Gem 57 Gooding 80 Idaho 215 Jefferson 127 Jerome 110 Kootenai 154 Latah 115 Lemhi 112 Lewis 21 Lincoln 53 Madison 80 Minidoka 66 Nez Perce 71 Oneida 23 Owyhee 48 Payette 65 Power 70 Shoshone 260 Teton 37 Twin Falls 126 Valley 149 Washington 80

Idaho 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 Idaho on the same metric.

OH

Ohio

4.74% top marginal rate
Structure
Progressive
Burden @ $100K
$26,729

CO

Colorado

4.82% top marginal rate
Structure
Progressive
Burden @ $100K
$8,965
Selected

ID

Idaho

4.90% top marginal rate
Structure
Progressive
Burden @ $100K
$4,616

IN

Indiana

5.22% top marginal rate
Structure
Progressive
Burden @ $100K
$19,495

KS

Kansas

5.26% top marginal rate
Structure
Progressive
Burden @ $100K
$24,894

Bridges Needing Most Attention in Idaho

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

STC 6774;TETON HWY

Poor

Over: S.FK.TETON RIVER

0.5 N. TETON, Fremont, ID

Built 1977 Load: 0.9 t ADT: 1,200

RIVER ROAD

Poor

Over: VINSON WASH

2.0 N. 2.6 W. GRAND VIEW, Owyhee, ID

Built 1930 Load: 0.9 t ADT: 60

SWAMP ROAD

Poor

Over: CAMAS CREEK

1.5 S. 0.3 E. HILL CITY, Camas, ID

Built 1965 Load: 1.8 t ADT: 40

ELK SUMMIT RD

Poor

Over: SOUTH FORK SALMON RIVER

14.6 N 4.3 W YELLOW PINE, Valley, ID

Built 1934 Load: 1.8 t ADT: 10

ROAD 50343

Poor

Over: LOGAN CREEK

NO DATA ENTERED, Valley, ID

Built 1980 Load: 2.6 t ADT: 50

200 SOUTH ROAD

Poor

Over: CAMAS CREEK

1.9 S. 6.8 E. FAIRFIELD, Camas, ID

Built 1920 Load: 2.7 t ADT: 30

All Bridges in Idaho

FOREST ROAD 651

Poor

Over: SELWAY RIVER-OHARA

7 MI. FROM LOWELL ID, Idaho, ID

Built 1956 Load: 21.7 t ADT: 50

I 15 NBL

Poor

Over: HUMPHREY ROAD IC

AT HUMPHREY, Clark, ID

Built 1966 Load: 21.8 t ADT: 1,750

SH 55

Poor

Over: UPRR;N.FK.PAYETTE RIVER

3.0 N. SMITHS FERRY, Valley, ID

Built 1933 Load: 21.8 t ADT: 4,200

EAST FORK ROAD

Poor

Over: S.FK.SALMON RIVER

14.5 W. YELLOW PINE, Valley, ID

Built 1940 Load: 21.8 t ADT: 40

S5786;COLBURN CULV

Poor

Over: GROUSE CREEK

5.0 E. COLBURN, Bonner, ID

Built 1941 Load: 21.8 t ADT: 840

1300 N

Poor

Over: HENRYS FK.SNAKE R;FRITZ

1.1 S. 4.0 W. ASHTON, Fremont, ID

Built 1967 Load: 21.8 t ADT: 50

8 MILE ROAD

Poor

Over: BEAR RIVER

3.2 S. 4.1 E.SODA SPRINGS, Caribou, ID

Built 1972 Load: 21.8 t ADT: 100

14TH AVE N.

Poor

Over: INDIAN CREEK

IN NAMPA;14TH AVE.N., Canyon, ID

Built 1947 Load: 22.7 t ADT: 930

S5907;DEEP CRK LP

Poor

Over: BNRR;UPRR & DEEP CREEK

0.1 S. NAPLES, Boundary, ID

Built 1936 Load: 22.7 t ADT: 880

SQUAW CREEK ROAD

Poor

Over: SQUAW CREEK

1.5 N. 3.4 W. CLAYTON, Custer, ID

Built 1960 Load: 22.7 t ADT: 330

SQUAW CREEK RD

Poor

Over: SQUAW CREEK

2.9 N. 3.5 W. CLAYTON, Custer, ID

Built 1960 Load: 22.7 t ADT: 330

BEAVER-LOON ROAD

Poor

Over: JORDAN CREEK

NO DATA ENTERED, Custer, ID

Built 1957 Load: 23.0 t ADT: 100

SH 75

Poor

Over: YANKEE FK OF SALMON RIVR

1.0 E. SUNBEAM, Custer, ID

Built 1934 Load: 23.6 t ADT: 660

STC 5804;WESTSIDE

Poor

Over: MYRTLE CREEK

0.8N. 4.8W. BONNERS FERRY, Boundary, ID

Built 1958 Load: 23.6 t ADT: 300

BURNT LOG ROAD

Poor

Over: JOHNSON CREEK

.5 MI NW LANDMARK AIRSTRP, Valley, ID

Built 1977 Load: 23.7 t ADT: 30

BOULDER CREEK ROAD

Poor

Over: MORES CREEK

5 MI NE IDAHO CITY, Boise, ID

Built 1982 Load: 24.0 t ADT: 50

FDR

Poor

Over: VALLEY CREEK

6 MILES NW OF STANLEY, Custer, ID

Built 1950 Load: 24.0 t ADT: 50

MOCCASIN-NAPIAS RD

Poor

Over: NAPIAS CREEK

NO DATA ENTERED, Lemhi, ID

Built 1953 Load: 24.3 t ADT: 25

STC 7787;PLYMOUTH

Poor

Over: BOISE RIVER & CANAL

CALDWELL NCL, Canyon, ID

Built 1922 Load: 24.5 t ADT: 2,000

STC 3851;HEXON RD

Poor

Over: BOISE RIVER

0.4 S. 1.2 W. PARMA, Canyon, ID

Built 1954 Load: 24.5 t ADT: 560

PINE DRIVE; NF 301

Poor

Over: W.FK.ST MARIES RIVER

2.0 S. 0.8 W. CLARKIA, Shoshone, ID

Built 1973 Load: 24.5 t ADT: 130

OLD HWY 91

Poor

Over: UPRR;N.SPENCER RR OP

13.1 N. 5.2 W. SPENCER, Clark, ID

Built 1936 Load: 24.5 t ADT: 50

850 EAST ROAD

Poor

Over: EAST MAIN CANAL

7.3 N. 4.0 W. RICHFIELD, Lincoln, ID

Built 1965 Load: 25.2 t ADT: 30

SQUAW CREEK RD

Poor

Over: SQUAW CREEK

2.9 W. CLAYTON, Custer, ID

Built 1960 Load: 25.2 t ADT: 100

NO DATA ENTERED

Poor

Over: OROFINO CREEK

MILL POND, Clearwater, ID

Built 1958 Load: 25.3 t ADT: 140

STC 1757;MAIN ST

Poor

Over: PORTNEUF RIVER

IN LAVA HOT SPRINGS, Bannock, ID

Built 1962 Load: 25.4 t ADT: 1,200

STC7151;BENTON ST

Poor

Over: PORTNEUF RIVER

IN POCATELLO;BENTON ST, Bannock, ID

Built 1969 Load: 25.4 t ADT: 2,800

I 86B ROCKLAND IC

Poor

Over: I 86 EB-WB;ROCKLAND IC

2.9 W. AMERICAN FALLS, Power, ID

Built 1959 Load: 26.3 t ADT: 1,500

SH 33

Poor

Over: SPRING CREEK

1.3 E. TETONIA, Teton, ID

Built 1975 Load: 26.3 t ADT: 5,500

US 91

Poor

Over: GIBSON LATERAL CANAL

5.7 N. FORT HALL, Bingham, ID

Built 1923 Load: 26.3 t ADT: 4,000

30 SOUTH ROAD

Poor

Over: MILNER GOODING CANAL

0.3 S. 1.8 E. SHOSHONE, Lincoln, ID

Built 1977 Load: 26.3 t ADT: 20

MILL ROAD

Poor

Over: I 90;MILL ROAD IC

0.4 W. MULLAN, Shoshone, ID

Built 1963 Load: 26.3 t ADT: 110

SCOTT RD; W 100 S

Poor

Over: ABERDEEN SPRINGFIELD CNL

0.5 S. 0.9 W. ROCKFORD, Bingham, ID

Built 1964 Load: 27.0 t ADT: 190

I 84 WB ON RAMP

Poor

Over: BOISE RIVER;RAMP DA BR

IN CALDWELL, Canyon, ID

Built 1980 Load: 27.2 t ADT: 5,000

STC5751;OLD HWY 95

Poor

Over: SIRR & UPRR;S.ATHOL OP

1.5 S. ATHOL, Kootenai, ID

Built 1929 Load: 27.2 t ADT: 530

FOREST ROAD 1614

Poor

Over: FRENCH CREEK

18 MI. FROM RIGGINS ID, Idaho, ID

Built 1957 Load: 27.9 t ADT: 50

US 30

Poor

Over: UPRR;BICKEL OVERPASS

4.3 E. HANSEN, Twin Falls, ID

Built 1936 Load: 28.1 t ADT: 2,400

SMA 7611;W. BRIDGE

Poor

Over: SNAKE RIVER

IN BLACKFOOT;W.BRIDGE ST., Bingham, ID

Built 1936 Load: 28.1 t ADT: 6,800

CO. RD.;OLD US 93

Poor

Over: U CANAL

12.5 N. TWIN FALLS, Jerome, ID

Built 1934 Load: 28.1 t ADT: 5

STC2784;MILLARD RD

Poor

Over: MILNER GOODING CANAL

1.5 S. 2.6 E. SHOSHONE, Lincoln, ID

Built 1955 Load: 28.1 t ADT: 190

N 1600 E

Poor

Over: ST ANTHONY CANAL

0.7 N. EGIN, Fremont, ID

Built 1971 Load: 28.1 t ADT: 70

US 20 FRONTAGE RD

Poor

Over: FALL RIVER OVERFLOW

1.5 N. 3.7 E. ST ANTHONY, Fremont, ID

Built 1932 Load: 28.1 t ADT: 10

FS ROUTE NO. 2706

Poor

Over: GRANITE CREEK

GRANITE CREEK, Bonner, ID

Built 1964 Load: 28.2 t ADT: 50

FS ROUTE NO. 308

Poor

Over: KALISPELL CREEK

KALISPELL CREEK, Bonner, ID

Built 1955 Load: 28.8 t ADT: 50

I 90 WBL

Poor

Over: PEDESTRIAN/BIKE PATH

COEUR DALENE NWCL, Kootenai, ID

Built 1971 Load: 29.0 t ADT: 31,500

PARKINSON ROAD

Poor

Over: CUB RIVER

IN FRANKLIN;PARKINSON RD., Franklin, ID

Built 1926 Load: 29.0 t ADT: 310

POTLATCH ROAD

Poor

Over: BLACK PRINCE TRESTLE

6.6 E. CALDER, Shoshone, ID

Built 1912 Load: 29.0 t ADT: 100

US 20 FRONTAGE RD

Poor

Over: N. BRANCH FALL RIVER CNL

1.4 N. 3.5 E. ST ANTHONY, Fremont, ID

Built 1932 Load: 29.0 t ADT: 10

PR

Poor

Over: NORTH FORK WOOD RIVER

2 MILES NORTH SNRA HQDS, Blaine, ID

Built 1950 Load: 29.2 t ADT: 50

NO DATA ENTERED

Poor

Over: YELLOWJACKET CREEK

NO DATA ENTERED, Lemhi, ID

Built 1962 Load: 29.8 t ADT: 50

Showing 4,501-4,550 of 4,616 bridges

Related

All states → | National rankings → | Understanding conditions → | Retired SD term explained →
Data sourced from the FHWA National Bridge Inventory (NBI), latest released cycle. See our methodology for details. Retrieved and formatted by PlainBridges.

Disclaimer: This information is provided for informational purposes only and does not constitute professional advice. Data is sourced from the FHWA National Bridge Inventory (NBI). Poor condition is an inspection-record category, not a closure or unsafe-to-cross designation. Consult the bridge owner for current status.

Understanding Bridge Conditions

How FHWA rates bridge condition on a 0-9 scale.

Check Your Daily Bridges

How to look up bridge condition data for bridges on your route.

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

What to do with this

Use Idaho's inventory picture to drill to a county or a specific span.

NBI condition ratings are inventory snapshots, not live crossing-safety verdicts.

Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. Idaho Good/Fair/Poor shares and county rollups on this page are computed from the same NBI extract as the national boards; no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2024 NBI release. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.