County profile · official public datasets

Stanley County, SD

37 public highway bridges tracked in the FHWA National Bridge Inventory: 37.8% rated Good, 48.6% Fair, 13.5% Poor.

37
Public bridges: 37.8%
Good condition: 13.5%
Poor condition

The verdict

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

Stanley County pairs a better-than-median Poor-condition share among rated counties in the state with an older average build year than the state inventory.

Top 45%
lowest Poor share in state: 13.5%
Poor-condition share: 37
public highway bridges: 1969
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.

Stanley County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Stanley County ranks #30 of 66 South Dakota counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 13.5%). Stanley County, South Dakota contains 37 public highway bridges. Roughly 37.8% are rated “Good,” 48.6% “Fair,” and 13.5% “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 Stanley County

Good condition

37.8%

14 of 37 rated 7-9

Fair condition

48.6%

18 of 37 rated 5-6

Poor condition

13.5%

5 of 37 rated 4 or below

In-state Poor-share rank

#30 of 66

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

Condition distribution

Share of 37 NBI-tracked bridges by lowest applicable component rating.

Good

37.8% (14)

Fair

48.6% (18)

Poor

13.5% (5)

Stanley County's Poor-condition bridges carry 450 vehicle crossings a day

That is 2% of the county's reported daily bridge traffic on 13.5% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 90 crossings a day against 554 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 37 of 37 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

56.8% of Stanley County's bridges have passed the 50-year mark

21 of the 37 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 37.8% 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 46.7% of the county's Poor-condition bridge traffic

FAS 3214 over DAN POWELL CK, built 1936, carries 210 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 5-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 450 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1920s

4
1930s

3
1950s

2
1960s

10
1970s

3
1980s

3
1990s

7
2000s

4
2010s

1

What this shows Construction peaked in the 1960s, when 10 of the county's bridges still in the inventory were built, which is 27% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year is 1969, 6 years older than the South Dakota average of 1975.

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

The 5 South Dakota counties nearest Stanley County in number of bridges, with their condition splits. Its 13.5% Poor share is the 3rd-lowest of these 6. Its average build year of 1969 against a peer-group mean of 1965 is in line with the group.

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

Bridge inventory size and condition shares for Stanley County and the 5 South Dakota counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Marshall County	39	15.4%	51.3%	33.3%	1965
Brule County	38	34.2%	63.2%	2.6%	1966
Jones County	37	13.5%	81.1%	5.4%	1965
Stanley County (this page)	37	37.8%	48.6%	13.5%	1969
Jerauld County	35	20%	54.3%	25.7%	1967
Kingsbury County	35	17.1%	54.3%	28.6%	1964

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

Similar inventory size

Nearest county inventories outside SD (37 bridges here).

Sitka City and County, AK · 37 bridges
Suwannee County, FL · 37 bridges
Teton County, ID · 37 bridges
Dickinson County, MI · 37 bridges

Similar average build year

Nearest mean year-built outside SD (1969 here).

Cook County, IL · avg 1969 · 1,721 bridges
Fresno County, CA · avg 1969 · 916 bridges
Cuyahoga County, OH · avg 1969 · 871 bridges
Ventura County, CA · avg 1969 · 501 bridges

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

All 37 Good 14 Fair 18 Poor 5

All bridges (37)

Sort:

Stanley County Bridge Snapshot

Condition distribution

Stanley County's Poor-condition bridges carry 450 vehicle crossings a day

56.8% of Stanley County's bridges have passed the 50-year mark

One structure carries 46.7% of the county's Poor-condition bridge traffic

How Stanley 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 (37)

HWY 63 SERVICE RD

COUNTY RD

STATE PARK RD

HWY 34 SERVICE RD

US014

US014

FAS 3214 270 AVE

FAS 3214 270 AVE

US014

US014

STATE HIGHWAY 514

FAS 3214

US083

SD1806

SD1806

FAS 6280

SD1806

IRR SD1806

FAS 3214

FAS6450

FAS 3215 280 AVE

BAD RIVER RD

BAD RIVER RD

US014

SD1806EF

SD1806EF

SD1806

US014

US014

SD1806

FAS 3214 280 AVE

US014

PLEASANT VALLEY RD

FAS 3214

US014 EF

US014 EF

STAE HIGHWAY 1806

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