How many bridges are in South Dakota?

South Dakota has 5,905 public highway bridges tracked in the FHWA National Bridge Inventory. View detailed condition data for each bridge on PlainBridges.

What percentage of bridges in South Dakota are structurally deficient?

16.2% of bridges in South Dakota are classified as structurally deficient by the FHWA, compared to a national average of 7.0%.

State profile · Above national median SD

South Dakota bridge safety

Condition ratings, load ratings, and structural-deficiency data for every public highway bridge in South Dakota — drawn straight from the FHWA National Bridge Inventory.

Reviewed byPlainbridges Editorial, Plain Bridges Editorial Team · June 6, 2026

5,905
Public bridges: 31.9%
Good condition: 16.2%
Poor condition: 16.2%
Structurally deficient

Total Bridges

5,905

Public highway bridges in South Dakota

Good Condition

31.9%

1,885 bridges rated 7-9

-18.1pp vs 50% benchmark

Poor Condition

16.2%

959 bridges rated 0-4

Structurally Deficient

16.2%

959 bridges flagged for repair priority

9.2pp vs national avg 7.0%

South Dakota vs national bridge condition

South Dakota — Good condition share 31.9%

National avg

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

South Dakota — Structurally deficient share 54.1%

National avg

Lower is better. Bar maxes at 30% (worst-state ceiling). National average sits at 7.0%.

Condition Distribution

Bridge inventory deck-condition mix — South Dakota (FHWA NBI)

Counties (66)

Aurora 61 Beadle 153 Bennett 15 Bon Homme 126 Brookings 234 Brown 170 Brule 38 Buffalo 25 Butte 143 Campbell 15 Charles Mix 103 Clark 21 Clay 94 Codington 74 Corson 49 Custer 95 Davison 125 Day 37 Deuel 72 Dewey 28 Douglas 44 Edmunds 20 Fall River 80 Faulk 46 Grant 205 Gregory 51 Haakon 69 Hamlin 62 Hand 126 Hanson 62 Harding 49 Hughes 41 Hutchinson 161 Hyde 23 Jackson 89 Jerauld 35 Jones 37 Kingsbury 35 Lake 79 Lawrence 136 Lincoln 207 Lyman 114 Marshall 39 McCook 98 McPherson 14 Meade 217 Mellette 28 Miner 64 Minnehaha 395 Moody 87 Oglala Lakota 34 Pennington 350 Perkins 60 Potter 24 Roberts 157 Sanborn 53 Spink 176 Stanley 37 Sully 31 Todd 24 Tripp 90 Turner 143 Union 172 Walworth 34 Yankton 99 Ziebach 30

South Dakota vs nearby ranks

Adjacent states on the structurally deficient leaderboard (lower share = better)

States are ranked by share of bridges flagged structurally deficient — the FHWA classification for any span where deck, superstructure, or substructure carries a condition rating of 4 or below. Lower percentages indicate stronger maintenance funding and inspection follow-through. States here sit immediately above and below South Dakota on the same metric.

Guam

15.25% top marginal rate

Structure: Progressive
Burden @ $100K: $59

West Virginia

16.02% top marginal rate

Structure: Progressive
Burden @ $100K: $7,679

Selected

South Dakota

16.24% top marginal rate

Structure: Progressive
Burden @ $100K: $5,905

Iowa

20.01% top marginal rate

Structure: Progressive
Burden @ $100K: $20,753

Virgin Islands

29.17% top marginal rate

Structure: Progressive
Burden @ $100K: $24

Bridges Needing Most Attention in South Dakota

Six lowest-condition bridges in South Dakota, ranked by composite NBI rating. Each is inspected at least every 24 months.

483 AVENUE

Structurally Deficient

Over: WHETSTONE RV

4.8E & 3.2N MILBANK, Grant, SD

Built 1962 Load: 0.9 t ADT: 25

202ND ST.

Structurally Deficient

Over: BEAR BUTTE CK

5.3E BEAR BUTTE, Meade, SD

Built 2000 Load: 0.9 t ADT: 50

45980 303 ST.

Structurally Deficient

Over: VERMILLION RV

6S & 7.8E IRENE, Clay, SD

Built 1909 Load: 1.8 t ADT: 15

460th Avenue

Structurally Deficient

Over: Big Coulee Creek

4S & 2W of Peever, Roberts, SD

Built 1950 Load: 2.2 t ADT: 22

197TH ST

Structurally Deficient

Over: TURTLE CK

1N & 1E ST LAWRENCE, Hand, SD

Built 1925 Load: 2.5 t ADT: 25

242 ST

Structurally Deficient

Over: CK

1.8E 11.0N PLANKINTON, Aurora, SD

Built 1917 Load: 2.7 t ADT: 101

All Bridges in South Dakota

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Publisher	Kiznis Studio
Sources	FHWA National Bridge Inventory, public U.S. government datasets

South Dakota vs national bridge condition

Condition Distribution

Counties (66)

Bridges Needing Most Attention in South Dakota

483 AVENUE

202ND ST.

45980 303 ST.

460th Avenue

197TH ST

242 ST

All Bridges in South Dakota

I090 W

I090 E

US014 WB OFF/90 E2

US014 E

I090 E

I090 W

I090 W

I090 E

IRR US012

IRR 144 ST

IRR I029 S

IRR I029 N

IRR SD015

IRR I029 S

IRR I029 N

IRR I029 S

IRR EASTMAN RD

IRR I029 N

IRR I029 S

IRR 129 ST

IRR COUNTY RD

IRR SD010

IRR I029 N

IRR 117 ST

IRR 113 ST

IRR I029 S

IRR I029 N

IRR 104 ST

IRR I029 S

IRR I029 N

IRR I029 S

IRR I029 N

I029 S

SD046

298 ST

300 ST

I029 N

306 ST (FAS 6370)

307 ST

309 ST

SD048

SD050

472 AVE

475 AVE

I029 S

I029 N

I029 L

478 AVE

480 AVE (FAS 6285)

330TH STREET

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