County profile · official public datasets

Turner County, SD

143 public highway bridges tracked in the FHWA National Bridge Inventory: 38.5% rated Good, 35.7% Fair, 25.9% Poor.

143
Public bridges: 38.5%
Good condition: 25.9%
Poor condition

The verdict

According to the Federal Highway Administration's 2024 National Bridge Inventory.

Turner County pairs a higher-than-median Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

55th
of 66 on Poor share: 25.9%
Poor-condition share: 143
public highway bridges: 1984
avg year built

Poor is an FHWA condition category from the lowest applicable component rating (4 or below), not a live crossing-safety or closure decision. Rankings cover counties with at least five public highway bridges.

Turner County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Turner County ranks #55 of 66 South Dakota counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 25.9%). Turner County, South Dakota contains 143 public highway bridges. Roughly 38.5% are rated “Good,” 35.7% “Fair,” and 25.9% “Poor.” Poor means the lowest applicable deck, superstructure, substructure, or culvert rating is 4 or below on the 0–9 NBI scale. It is a condition category, not a live safety or closure decision.

Responsible agencies inspect covered bridges on risk-based intervals under current NBIS rules and submit inventory data to FHWA annually. The list below shows every NBI-tracked bridge in the county. Use the “Sort by” controls to change the ordering, and click any row for its reported inspection date, traffic count, and condition fields.

Source: FHWA National Bridge Inventory. See methodology for full definitions.

Total bridges

143

Public highway bridges in Turner County

Good condition

38.5%

55 of 143 rated 7-9

Fair condition

35.7%

51 of 143 rated 5-6

Poor condition

25.9%

37 of 143 rated 4 or below

In-state Poor-share rank

#55 of 66

Among South Dakota counties with 5+ bridges, lower share ranks better

Condition distribution

Share of 143 NBI-tracked bridges by lowest applicable component rating.

Good

38.5% (55)

Fair

35.7% (51)

Poor

25.9% (37)

Turner County's Poor-condition bridges carry 4,094 vehicle crossings a day

That is 7.8% of the county's reported daily bridge traffic on 25.9% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 111 crossings a day against 647 for a Good-condition one. A Poor rating is a condition category, not a closure or a live safety judgement; it means the lowest applicable component rating is 4 or below.

Computed over the 143 of 143 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

35.7% of Turner County's bridges have passed the 50-year mark

51 of the 143 bridges with a recorded construction year were built in 1974 or earlier. Age alone is not a defect: a well-maintained older bridge can rate Good, and 38.5% of this county's inventory does. Even so, this older cohort is the population from which future Poor ratings are drawn, which is why the age profile below matters alongside the condition split above.

Cutoff derives from the 2024 release year minus a 50-year design life. Source: FHWA National Bridge Inventory, 2024 release.

One structure carries 18.5% of the county's Poor-condition bridge traffic

45520 275 ST over WEST FORK VERMILLION RV, built 1952, carries 758 vehicles a day, the most of any Poor-rated structure here. The county's Poor-condition exposure is concentrated rather than evenly spread, so the 37-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 4,094 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1910s

4
1930s

5
1940s

9
1950s

12
1960s

15
1970s

10
1980s

13
1990s

28
2000s

20
2010s

23
2020s

4

What this shows Construction peaked in the 1990s, when 28 of the county's bridges still in the inventory were built, which is 19.6% of those with a recorded year. That cohort is now 25 to 34 years old in the 2024 inventory. Its average build year is 1984, 9 years newer than the South Dakota average of 1975.

How Turner County compares with South Dakota's closest counties by inventory size

The 5 South Dakota counties nearest Turner County in number of bridges, with their condition splits. Its 25.9% Poor share is the 4th-lowest of these 6. Its average build year of 1984 against a peer-group mean of 1968 is 16 years newer.

Showing the 5 closest of 65 South Dakota counties eligible for comparison.

Bridge inventory size and condition shares for Turner County and the 5 South Dakota counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Roberts County	157	22.9%	52.9%	24.2%	1970
Beadle County	152	19.1%	47.4%	33.6%	1955
Butte County	143	30.8%	57.3%	11.9%	1976
Turner County (this page)	143	38.5%	35.7%	25.9%	1984
Lawrence County	136	36%	51.5%	12.5%	1980
Bon Homme County	126	21.4%	50.8%	27.8%	1961

Each share is of that county's own total tracked bridges; peers are the counties with 5 or more bridges whose inventory size is closest to Turner County's. Source: FHWA National Bridge Inventory, 2024 release.

Nationwide counties with similar inventory size or average build year

Two NBI-derived peer sets for Turner County, both outside South Dakota so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside SD (143 bridges here).

Franklin County, AR · 143 bridges
San Francisco County, CA · 143 bridges
Woodson County, KS · 143 bridges
Adair County, KY · 143 bridges

Similar average build year

Nearest mean year-built outside SD (1984 here).

Hennepin County, MN · avg 1984 · 936 bridges
Duval County, FL · avg 1984 · 831 bridges
El Paso County, CO · avg 1984 · 686 bridges
Bell County, TX · avg 1984 · 660 bridges

Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.

All 143 Good 55 Fair 51 Poor 37

Good-condition bridges (55)

Sort:

Turner County Bridge Snapshot

Condition distribution

Turner County's Poor-condition bridges carry 4,094 vehicle crossings a day

35.7% of Turner County's bridges have passed the 50-year mark

One structure carries 18.5% of the county's Poor-condition bridge traffic

How Turner County compares with South Dakota's closest counties by inventory size

Nationwide counties with similar inventory size or average build year

Similar inventory size

Similar average build year

Good-condition bridges (55)

27550 456 AVE

46030 272 ST

44020 290 ST.

44150 282ND ST

44640 283 AVE

28650 447TH AVE

28480 448 AVE

27570 452 AVE

45270 290 ST.

454 AVE

48670 455 AVE

27360 456 AVE

45780 276 ST

29690 458TH AVE

45880 292ND ST

45970 294TH ST

28610 460 AVE

46330 289 ST

COUNTY RD

458TH AVENUE

45500 282 ST

SD044

28010 454 AVE

US018

US018

44950 282 ST

269 ST

459TH AVE

45940 280 ST

45890 291ST STREET

US018

US018

458TH AVENUE

SD044

COUNTY RD

45290 280 ST

447TH AVE

US018

SD019

US018

US018

US018

27370 461 AVE

SD044

US018

SD019

SD044

SD019

COUNTY RD

SD044

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