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

SUNNY SIDE ROAD

Fair

Over: BNRR;KOOTENAI OP

0.8 N. 4.4 E. KOOTENAI, Bonner, ID

Built 1994 Load: 30.8 t ADT: 1,200

THEATRE ROAD

Fair

Over: S.FK.CDA R;SMELTERVILLE

0.4 N. 0.1 W.SMELTERVILLE, Shoshone, ID

Built 1963 Load: 30.8 t ADT: 200

STATELINE RD;WY114

Fair

Over: TINCUP CREEK

3.5 Miles N. of ETNA, Caribou, ID

Built 1970 Load: 30.8 t ADT: 121

55TH EAST ROAD

Fair

Over: ANDERSON CANAL

4.5 N. IONA, Bonneville, ID

Built 1954 Load: 30.8 t ADT: 1,300

STC6868;TRAIL CRK

Fair

Over: N. FORK BIG LOST RIVER

18.9 N.E. SUN VALLEY, Custer, ID

Built 1970 Load: 30.8 t ADT: 410

TROUT ROAD

Fair

Over: SEVEN SUCKERS DITCH

IDFG EAGLE HATCHERY, Ada, ID

Built 1950 Load: 30.8 t ADT: 50

INDIAN CREEK RD

Fair

Over: INDIAN CREEK(#3)

22.0 NW SALMON, Lemhi, ID

Built 1970 Load: 30.8 t ADT: 15

STC 6706;HITT ROAD

Fair

Over: RIRIE OUTLET CANAL

1.0 S. 1.5 W. UCON, Bonneville, ID

Built 2005 Load: 31.1 t ADT: 3,300

FOREST ROAD 1194

Fair

Over: SO. FK. RED RIVER

NO DATA ENTERED, Idaho, ID

Built 1969 Load: 31.1 t ADT: 40

FOREST ROAD 1809

Fair

Over: AMERICAN RIVER

NO DATA ENTERED, Idaho, ID

Built 1961 Load: 31.1 t ADT: 50

FS ROUTE NO. 2798

Fair

Over: CANUCK CREEK

CANUCK CR, Boundary, ID

Built 1957 Load: 31.4 t ADT: 50

FDR 292

Fair

Over: PALOUSE RIVER

2 MI E OF STATE HWY 6, Latah, ID

Built 1959 Load: 31.4 t ADT: 20

100 SOUTH ROAD

Fair

Over: G CANAL

0.1 S. 0.7 W. DECLO, Cassia, ID

Built 1989 Load: 31.5 t ADT: 250

S3784;LOCUST GROVE

Fair

Over: KUNA CANAL

0.1 N. 2.3 E. KUNA, Ada, ID

Built 1949 Load: 31.5 t ADT: 610

STC 8317;DUFF LANE

Fair

Over: WILLOW CREEK

2.1 N. 1.5 E. MIDDLETON, Canyon, ID

Built 1983 Load: 31.5 t ADT: 740

CANYON CREEK ROAD

Fair

Over: FEEDER CANAL

5.0N 0.3E MOUNTAIN HOME, Elmore, ID

Built 1978 Load: 31.5 t ADT: 80

STC9589;SALES YARD

Fair

Over: FARMERS COOP CANAL

1.7 S. 0.2 W. EMMETT, Gem, ID

Built 1970 Load: 31.5 t ADT: 320

STC 3944;ELO ROAD

Fair

Over: LAKE FORK CREEK

2.7 S. 2.6 E. MCCALL, Valley, ID

Built 1973 Load: 31.5 t ADT: 1,400

WIGGINS ROAD

Fair

Over: KEITHLY CREEK

2.7 N. MIDVALE, Washington, ID

Built 1984 Load: 31.5 t ADT: 50

S5739;SPIRIT LAKE

Fair

Over: SPIRIT LAKE(CAUSEWAY BR)

0.4 S. 0.4 W. SPIRIT LAKE, Kootenai, ID

Built 1983 Load: 31.5 t ADT: 300

MEDIMONT ROAD

Fair

Over: CAVE LAKE CHANNEL

0.4 S. 0.5 E. MEDIMONT, Kootenai, ID

Built 1991 Load: 31.5 t ADT: 50

E 600 N

Fair

Over: CROSSCUT CANAL

1.9 S. 1.8 W. CHESTER, Fremont, ID

Built 1937 Load: 31.5 t ADT: 20

STC 6785;E 16TH N

Fair

Over: S.FK.TETON R;NE REXBURG

1.3 N. 2.6 E. REXBURG, Madison, ID

Built 1980 Load: 31.5 t ADT: 700

US 2

Fair

Over: PEND OREILLE R;OLDTOWN B

0.1 E. JCT. 41;IN OLDTOWN, Bonner, ID

Built 1988 Load: 31.8 t ADT: 11,000

SH 3

Fair

Over: ARROW GULCH

8 S. JULIAETTA, Nez Perce, ID

Built 1968 Load: 31.8 t ADT: 2,200

SH 3

Fair

Over: FOURTH OF JULY CREEK

3.1 N. ROSE LK.;JCT I 90, Kootenai, ID

Built 1962 Load: 31.8 t ADT: 2,400

SH 8

Fair

Over: PARADISE CRK;PED WALKWAY

EAST SIDE OF MOSCOW, Latah, ID

Built 1983 Load: 31.8 t ADT: 11,500

US 12

Fair

Over: POST OFFICE CREEK

48.1 E. LOWELL, Idaho, ID

Built 1960 Load: 31.8 t ADT: 530

I 15 NBL

Fair

Over: STC 1758;UPRR;INKOM OP

1.3 S. INKOM, Bannock, ID

Built 1963 Load: 31.8 t ADT: 8,000

I 15 NBL

Fair

Over: I 15B;S.INKOM IC

0.5 E. INKOM, Bannock, ID

Built 1962 Load: 31.8 t ADT: 8,000

I 15 SBL

Fair

Over: I 15B;S.INKOM IC

0.5 E. INKOM, Bannock, ID

Built 1962 Load: 31.8 t ADT: 8,000

I 15 NBL

Fair

Over: BEAVER CREEK

5.0 N. HAMER, Jefferson, ID

Built 1963 Load: 31.8 t ADT: 1,700

US 20 EBL

Fair

Over: SNAKE RIVER;LORENZO BR.

0.3 N. LORENZO, Jefferson, ID

Built 1980 Load: 31.8 t ADT: 15,000

US 20 WBL

Fair

Over: AMERICANA BLVD;15TH ST.

IN BOISE; FRONT STREET, Ada, ID

Built 1992 Load: 31.8 t ADT: 31,500

SH 21

Fair

Over: S.FK.PAYETTE RIVER

15 NE. LOWMAN, Boise, ID

Built 1970 Load: 31.8 t ADT: 1,100

SH 24

Fair

Over: 702-A CANAL

13.3 E. SHOSHONE, Lincoln, ID

Built 1976 Load: 31.8 t ADT: 670

US 93

Fair

Over: LITTLE WOOD RIVER

4.9 SW. CAREY, Blaine, ID

Built 1987 Load: 31.8 t ADT: 860

US 93

Fair

Over: LITTLE WOOD RIVER

4.1 SW. CAREY, Blaine, ID

Built 1987 Load: 31.8 t ADT: 860

US 93

Fair

Over: LITTLE WOOD RIVER

IN CAREY, Blaine, ID

Built 1977 Load: 31.8 t ADT: 2,700

US 26

Fair

Over: EAGLE ROCK CANAL

1.0 S. RIRIE, Bonneville, ID

Built 1969 Load: 31.8 t ADT: 6,900

US 30

Fair

Over: US 30/US 93 INTERCHANGE

US 30/US 93 JUNCTION, Twin Falls, ID

Built 1997 Load: 31.8 t ADT: 10,500

US 30

Fair

Over: MAIN CANAL

1.6 E. MURTAUGH, Twin Falls, ID

Built 1956 Load: 31.8 t ADT: 2,700

SH 34

Fair

Over: BLACKFOOT RIVER

13.1 N. SODA SPRINGS, Caribou, ID

Built 1979 Load: 31.8 t ADT: 540

SH 39

Fair

Over: ABERDEEN WASTEWAY CANAL

0.6 N. ABERDEEN, Bingham, ID

Built 1968 Load: 31.8 t ADT: 2,000

SMA 7030;STATE ST

Fair

Over: DRY CREEK

AT EAGLE WCL, Ada, ID

Built 1959 Load: 31.8 t ADT: 4,700

SH 46

Fair

Over: NRTH GOODING MAIN CNL

5.3 N. GOODING, Gooding, ID

Built 1983 Load: 31.8 t ADT: 750

SH 51

Fair

Over: BRUNEAU RIVER

0.8 W. BRUNEAU, Owyhee, ID

Built 1955 Load: 31.8 t ADT: 1,200

SH 74

Fair

Over: LOW LINE CANAL

3.6 S. TWIN FALLS, Twin Falls, ID

Built 1956 Load: 31.8 t ADT: 1,100

SH 78

Fair

Over: CASTLE CREEK

18.8 E. MURPHY, Owyhee, ID

Built 1955 Load: 31.8 t ADT: 560

SH 78

Fair

Over: BROWN CREEK

5.6 W. HAMMETT, Owyhee, ID

Built 1954 Load: 31.8 t ADT: 460

Showing 1,751-1,800 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.