County profile · official public datasets

Oglala Lakota County, SD

34 public highway bridges tracked in the FHWA National Bridge Inventory: 55.9% rated Good, 38.2% Fair, 5.9% Poor.

34
Public bridges: 55.9%
Good condition: 5.9%
Poor condition

The verdict

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

Oglala Lakota County pairs a top-quartile lowest Poor-condition share among rated counties in the state with a newer average build year than the state inventory.

Top 18%
lowest Poor share in state: 5.9%
Poor-condition share: 34
public highway bridges: 1992
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.

Oglala Lakota County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Oglala Lakota County ranks #12 of 66 South Dakota counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 5.9%). Oglala Lakota County, South Dakota contains 34 public highway bridges. Roughly 55.9% are rated “Good,” 38.2% “Fair,” and 5.9% “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

Public highway bridges in Oglala Lakota County

Good condition

55.9%

19 of 34 rated 7-9

Fair condition

38.2%

13 of 34 rated 5-6

Poor condition

5.9%

2 of 34 rated 4 or below

In-state Poor-share rank

#12 of 66

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

Condition distribution

Share of 34 NBI-tracked bridges by lowest applicable component rating.

Good

55.9% (19)

Fair

38.2% (13)

Poor

5.9% (2)

Oglala Lakota County's Poor-condition bridges carry 60 vehicle crossings a day

That is 0.1% of the county's reported daily bridge traffic on 5.9% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 30 crossings a day against 1,731 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 34 of 34 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

26.5% of Oglala Lakota County's bridges have passed the 50-year mark

9 of the 34 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 55.9% 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 83.3% of the county's Poor-condition bridge traffic

MOCCASIN PARK RD over WHITE CLAY CREEK, built 1975, carries 50 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 2-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 60 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1930s

1
1940s

1
1950s

5
1960s

1
1970s

3
1980s

2
2000s

6
2010s

14
2020s

1

What this shows Construction peaked in the 2010s, when 14 of the county's bridges still in the inventory were built, which is 41.2% of those with a recorded year. That cohort is now 5 to 14 years old in the 2024 inventory. Its average build year is 1992, 17 years newer than the South Dakota average of 1975.

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

The 5 South Dakota counties nearest Oglala Lakota County in number of bridges, with their condition splits. Its 5.9% Poor share is the 3rd-lowest of these 6. Its average build year of 1992 against a peer-group mean of 1966 is 26 years newer.

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

Bridge inventory size and condition shares for Oglala Lakota County and the 5 South Dakota counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Jones County	37	13.5%	81.1%	5.4%	1965
Jerauld County	35	20%	54.3%	25.7%	1967
Kingsbury County	35	17.1%	54.3%	28.6%	1964
Day County	34	35.3%	29.4%	35.3%	1963
Oglala Lakota County (this page)	34	55.9%	38.2%	5.9%	1992
Walworth County	33	36.4%	60.6%	3%	1972

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 Oglala Lakota 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 Oglala Lakota County, both outside South Dakota so the neighborhoods are not the same-state size table above.

Similar inventory size

Nearest county inventories outside SD (34 bridges here).

Bear Lake County, ID · 34 bridges
Plaquemines County, LA · 34 bridges
Golden Valley County, ND · 34 bridges
Guayanilla County, PR · 34 bridges

Similar average build year

Nearest mean year-built outside SD (1992 here).

Johnson County, KS · avg 1992 · 781 bridges
Wake County, NC · avg 1992 · 760 bridges
Benton County, AR · avg 1992 · 410 bridges
Nodaway County, MO · avg 1992 · 396 bridges

Fair

Over: WHITE CLAY CK

11.2 NW OF PINE RIDGE, Oglala Lakota, SD

Built 2011 Load: 37.8 t ADT: 2,241

IRR BIA RTE 27

Fair

Over: WHITE RIVER

4 KM N OF ROCKYFORD, Oglala Lakota, SD

Oglala Lakota County Bridge Snapshot

Condition distribution

Oglala Lakota County's Poor-condition bridges carry 60 vehicle crossings a day

26.5% of Oglala Lakota County's bridges have passed the 50-year mark

One structure carries 83.3% of the county's Poor-condition bridge traffic

How Oglala Lakota 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

All bridges (34)

IRR US018

IRR US018

IRR US018

IRR US018

IRR BIA RTE 27

IRR BIA RTE 2

IRR US018

IRR US018

IRR BIA RTE 3202

IRR BIA RTE 2

IRR BIA RTE 41

IRR US018

IRR BIA RTE 27

IRR BIA RTE 8

IRR BIA RTE 33

IRR US018

IRR US018

IRR US018

IRR US018

IRR US018

IRR BIA RTE 36

IRR BIA ROUTE 32

IRR BIA RTE N

IRR BIA RTE N

IRR BIA RTE N

IRR BIA RTE 2

IRR BIA RTE 27

IRR US018

IRR US018

IRR US018

IRR US018

IRR US018

SMITHWICK ROAD

MOCCASIN PARK RD

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