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

US 93

Fair

Over: JIMMY BYRNES SLOUGH

0.8 E. RICHFIELD, Lincoln, ID

Built 1987 Load: 68.0 t ADT: 1,200

STC 3825 CNTRVILLE

Fair

Over: ELK CREEK

0.1 W. IDAHO CITY, Boise, ID

Built 1993 Load: 68.0 t ADT: 260

STC3883;CLEAR CRK

Fair

Over: GRIMES CREEK

5.0 S. 7.3 W. IDAHO CITY, Boise, ID

Built 1930 Load: 68.0 t ADT: 300

STC3895;YELLOWPINE

Fair

Over: JOHNSON CREEK

9 S. YELLOW PINE, Valley, ID

Built 1959 Load: 68.0 t ADT: 70

GULCH ROAD

Fair

Over: BIG WILLOW CREEK

3.1 N 3.4 E NEW PLYMOUTH, Payette, ID

Built 2011 Load: 69.3 t ADT: 50

WYLIE LANE

Fair

Over: FARMERS UNION CANAL

IN BOISE, Ada, ID

Built 1999 Load: 69.9 t ADT: 1,000

CAN-ADA ROAD

Fair

Over: MORA CANAL

2.8 S. 4.7 W. KUNA, Canyon, ID

Built 1992 Load: 69.9 t ADT: 300

SMA 7143;USTICK RD

Fair

Over: FIVE MILE CREEK

1.5 N. 1.2 W. MERIDIAN, Ada, ID

Built 1991 Load: 69.9 t ADT: 13,500

STC4693;S 550 E

Fair

Over: H CANAL

3.8 S. 3.0 W. DECLO, Cassia, ID

Built 2004 Load: 71.7 t ADT: 330

STP3728;LAKE HAZEL

Fair

Over: MASON CREEK FEEDER CANAL

3.7 N. 0.4 W. KUNA, Ada, ID

Built 1992 Load: 71.7 t ADT: 1,900

SMA 7093;MERIDIAN

Fair

Over: FIVE MILE CREEK

0.3 N. MERIDIAN, Ada, ID

Built 1991 Load: 71.7 t ADT: 17,500

N YELLOWSTONE HWY

Fair

Over: DRY BED CANAL

1.8 N. 1.2 E. RIGBY, Jefferson, ID

Built 1999 Load: 71.7 t ADT: 3,400

SMA3343;COLUMBIA

Fair

Over: RIDENBAUGH CANAL

2.8 N. 1.8 W. KUNA, Ada, ID

Built 1993 Load: 72.6 t ADT: 5,100

CEMETARY ROAD

Fair

Over: TETON CREEK

1.3 E. DRIGGS, Teton, ID

Built 2009 Load: 72.6 t ADT: 1,500

ALPINE STEET

Fair

Over: ELEC LGHT SWITCH LATERAL

IN BOISE, Ada, ID

Built 1970 Load: 73.5 t ADT: 960

S7993;AVIATION WAY

Fair

Over: CANYON HILL LATERAL

0.3 E 0.3 S CALDWELL, Canyon, ID

Built 2009 Load: 74.4 t ADT: 1,700

STC3756;DEER FLAT

Fair

Over: HIGH LINE CANAL

5.2 S. 1.2 W. NAMPA, Canyon, ID

Built 1990 Load: 74.4 t ADT: 930

N 3700 E ROAD

Fair

Over: PERRINE COULEE CANAL

1.3 W. 1.3 S. HANSEN, Twin Falls, ID

Built 1962 Load: 76.2 t ADT: 70

STC 5711;MOON PASS

Fair

Over: SQUAW CREEK

3.5 N. 1.6 E. AVERY, Shoshone, ID

Built 1909 Load: 78.0 t ADT: 360

I 86 & RAMPS

Fair

Over: LANES GULCH

17.9 W. AMERICAN FALLS, Power, ID

Built 1981 Load: 78.9 t ADT: 7,700

SMA 9183;TEN MILE

Fair

Over: RIDENBAUGH CANAL

0.3 S. OVERLAND-TEN MILE, Ada, ID

Built 1993 Load: 78.9 t ADT: 18,500

RAILROAD GRADE RD

Fair

Over: ST. JOE RIVER

16.0 E. ST. MARIES, Benewah, ID

Built 1908 Load: 78.9 t ADT: 40

EAST FORK ROAD

Fair

Over: E.FK. OF S.FK.SALMON RVR

14.0 W. YELLOW PINE, Valley, ID

Built 1941 Load: 79.8 t ADT: 40

CENARRUSA LANE

Fair

Over: LITTLE WOOD RIVER

0.6 S. 0.5 E. CAREY, Blaine, ID

Built 1940 Load: 80.7 t ADT: 35

STC6732;OLD HWY 91

Fair

Over: CAMAS CREEK

4.3 N. 1.0 W. HAMER, Jefferson, ID

Built 2001 Load: 80.7 t ADT: 280

STC9687;HS BEND RD

Fair

Over: FARMERS UNION CANAL

5.0 NW BOISE WCL, Ada, ID

Built 2012 Load: 81.3 t ADT: 6,600

STP 7446;SUNNYSIDE

Fair

Over: IDAHO CANAL

1.6 S 1.0 E IDAHO FALLS, Bonneville, ID

Built 2004 Load: 81.6 t ADT: 31,500

2950 EAST RD

Fair

Over: HEGLAR CANYON

14.9 NE MALTA, Cassia, ID

Built 2003 Load: 81.6 t ADT: 50

SMA 7028;BEACON LT

Fair

Over: FARMERS UNION CANAL

1.8 N. 0.3 W. EAGLE, Ada, ID

Built 1992 Load: 82.6 t ADT: 5,600

SMA7553;FEDERAL WY

Fair

Over: NEW YORK CANAL

1.1 SE BOISE SCL, Ada, ID

Built 1989 Load: 83.5 t ADT: 20,500

FRONTAGE ROAD

Fair

Over: DAIRY CANYON CREEK

13.2 W. AMERICAN FALLS, Power, ID

Built 1983 Load: 83.5 t ADT: 50

S3760;FLTG FEATHER

Fair

Over: DRY CREEK CANAL

1.0 N. 0.6 E. STAR, Ada, ID

Built 1987 Load: 83.5 t ADT: 3,300

E. STAGE COACH RD

Fair

Over: MORA CANAL

4.5 N. 0.5 W. MELBA, Canyon, ID

Built 2004 Load: 84.4 t ADT: 200

TINCUP JCT ROAD

Fair

Over: TINCUP CREEK;FREEDOM BR

1.0 N 1.0 W. FREEDOM WY, Caribou, ID

Built 2001 Load: 85.3 t ADT: 95

EYRIE WAY

Fair

Over: SAND CREEK

IN BOISE, Ada, ID

Built 2001 Load: 86.2 t ADT: 350

FIR GROVE ROAD

Fair

Over: CAMAS CREEK

3.4 S. 2.4 E. FAIRFIELD, Camas, ID

Built 1986 Load: 88.0 t ADT: 30

W 1000 S

Fair

Over: BIG COTTONWOOD CREEK

5.4 W. 6.5 S. PELLA, Cassia, ID

Built 1970 Load: 89.8 t ADT: 670

US 95

Fair

Over: COTTONWOOD CREEK

S. OF COTTONWOOD SCL, Idaho, ID

Built 1978 Load: 90.6 t ADT: 3,500

SH 3

Fair

Over: THORN CREEK

4.5 S. ST MARIES, Benewah, ID

Built 1939 Load: 91.6 t ADT: 2,200

AUSTIN ROAD

Fair

Over: FISH CREEK

3.3 N. 4.6 E. CAREY, Blaine, ID

Built 2009 Load: 91.6 t ADT: 30

STP 7403;FRANKLIN

Fair

Over: RIDENBAUGH CANAL

FRANKLIN RD IN BOISE, Ada, ID

Built 1995 Load: 95.3 t ADT: 20,500

STC4710;GRAVES CRK

Fair

Over: SALMON RIVER

9.4 S. 2.9 W. COTTONWOOD, Idaho, ID

Built 1973 Load: 95.3 t ADT: 30

STC 3881;STATE ST

Fair

Over: GALLOWAY CANAL

IN WEISER, Washington, ID

Built 1977 Load: 96.2 t ADT: 2,500

SH 8

Fair

Over: PEDESTRIAN PASS

7.8 E. MOSCOW ECL, Latah, ID

Built 2004 Load: 97.1 t ADT: 3,300

MORROW RESERVIOR R

Fair

Over: LITTLE CANYON CREEK

0.9N 0.4W GLENNS FERRY, Elmore, ID

Built 1995 Load: 98.0 t ADT: 160

STC3728;LAKE HAZEL

Fair

Over: FARR LATERAL CANAL

3.8 N. 3.0 E. KUNA, Ada, ID

Built 1992 Load: 98.9 t ADT: 5,100

SH 8

Fair

Over: BIG MEADOW CREEK

0.2 E. TROY CL, Latah, ID

Built 1979 Load: 99.9 t ADT: 2,800

SH 14

Fair

Over: ELK CREEK

0.2 W. ELK CITY, Idaho, ID

Built 1983 Load: 99.9 t ADT: 150

SH 162

Fair

Over: SEVEN MILE CREEK

4.4 S. KAMIAH, Idaho, ID

Built 1997 Load: 99.9 t ADT: 1,100

SH 78

Fair

Over: REYNOLDS CREEK

16.4 E. MARSING, Owyhee, ID

Built 1954 Load: 99.9 t ADT: 790

Showing 2,951-3,000 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.