County profile · official public datasets

Hanson County, SD

62 public highway bridges tracked in the FHWA National Bridge Inventory: 19.4% rated Good, 71% Fair, 9.7% Poor.

62
Public bridges: 19.4%
Good condition: 9.7%
Poor condition

The verdict

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

Hanson County posts a better-than-median Poor-condition share among rated counties in the state across rated county bridge inventory.

Top 30%
lowest Poor share in state: 9.7%
Poor-condition share: 62
public highway bridges: 1978
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.

Hanson County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Hanson County ranks #20 of 66 South Dakota counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 9.7%). Hanson County, South Dakota contains 62 public highway bridges. Roughly 19.4% are rated “Good,” 71% “Fair,” and 9.7% “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 Hanson County

Good condition

19.4%

12 of 62 rated 7-9

Fair condition

71%

44 of 62 rated 5-6

Poor condition

9.7%

6 of 62 rated 4 or below

In-state Poor-share rank

#20 of 66

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

Condition distribution

Share of 62 NBI-tracked bridges by lowest applicable component rating.

Good

19.4% (12)

Fair

71% (44)

Poor

9.7% (6)

Hanson County's Poor-condition bridges carry 415 vehicle crossings a day

That is 0.6% of the county's reported daily bridge traffic on 9.7% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 69 crossings a day against 89 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 62 of 62 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

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

31 of the 62 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 19.4% 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 39.8% of the county's Poor-condition bridge traffic

25810 416 AVENUE over JAMES RV, built 1959, carries 165 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 6-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 415 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1930s

1
1950s

6
1960s

23
1970s

5
1980s

12
1990s

4
2000s

6
2010s

3
2020s

2

What this shows Construction peaked in the 1960s, when 23 of the county's bridges still in the inventory were built, which is 37.1% of those with a recorded year. That cohort is now 55 to 64 years old in the 2024 inventory. Its average build year (1978) matches the South Dakota average (1975).

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

The 5 South Dakota counties nearest Hanson County in number of bridges, with their condition splits. Its 9.7% Poor share is the 2nd-lowest of these 6. Its average build year of 1978 against a peer-group mean of 1976 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 Hanson County and the 5 South Dakota counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Haakon County	69	29%	58%	13%	1974
Miner County	64	35.9%	37.5%	26.6%	1970
Hamlin County	62	41.9%	45.2%	12.9%	1978
Hanson County (this page)	62	19.4%	71%	9.7%	1978
Aurora County	61	42.6%	42.6%	14.8%	1967
Perkins County	60	51.7%	41.7%	6.7%	1989

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

Similar inventory size

Nearest county inventories outside SD (62 bridges here).

Conejos County, CO · 62 bridges
Pitkin County, CO · 62 bridges
Gulf County, FL · 62 bridges
Pickens County, GA · 62 bridges

Similar average build year

Nearest mean year-built outside SD (1978 here).

Orange County, CA · avg 1978 · 1,164 bridges
Sumner County, KS · avg 1978 · 659 bridges
Allen County, IN · avg 1978 · 613 bridges
Livingston County, IL · avg 1978 · 579 bridges

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

All 62 Good 12 Fair 44 Poor 6

All bridges (62)

Sort:

Hanson County Bridge Snapshot

Condition distribution

Hanson County's Poor-condition bridges carry 415 vehicle crossings a day

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

One structure carries 39.8% of the county's Poor-condition bridge traffic

How Hanson 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 (62)

25170 415 AVENUE

41550 258 STREET

26760 416 AVENUE

41790 246 ST.

24480 421 AVENUE

42300 256 STREET

42310 257 STREET

42910 259 ST.

42970 253 STREET

42970 260 STREET

26730 415 AVENUE

41440 257 STREET

41411 266 STREET

41690 257 AVENUE

24920 417 AVENUE

41760 248 STREET

41800 247 STREET

24550 419 AVENUE

42350 255 STREET

26760 426 AVENUE

42890 258 STREET

SD042

424 AVE

416 AVE (FAS 6229)

428 AVE

SD042

24510 420 AVENUE

SD042

SD042

SD025

SD262

I090 W

I090 E

I090 W

I090 E

25250 OLD MILL RD

I090 W

I090 E

I090 E

I090 W

SD038

SD038

24470 422 AVE.

42890 257 STREET

41740 255 STREET

25420 419 AVENUE

41220 264 STREET

42890 255 STR

42890 256 STREET

24940 416 AVENUE

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