County profile · official public datasets

Hamlin County, SD

62 public highway bridges tracked in the FHWA National Bridge Inventory: 41.9% rated Good, 45.2% Fair, 12.9% Poor.

62
Public bridges: 41.9%
Good condition: 12.9%
Poor condition

The verdict

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

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

Top 42%
lowest Poor share in state: 12.9%
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.

Hamlin County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Hamlin County ranks #28 of 66 South Dakota counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 12.9%). Hamlin County, South Dakota contains 62 public highway bridges. Roughly 41.9% are rated “Good,” 45.2% “Fair,” and 12.9% “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 Hamlin County

Good condition

41.9%

26 of 62 rated 7-9

Fair condition

45.2%

28 of 62 rated 5-6

Poor condition

12.9%

8 of 62 rated 4 or below

In-state Poor-share rank

#28 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

41.9% (26)

Fair

45.2% (28)

Poor

12.9% (8)

Hamlin County's Poor-condition bridges carry 624 vehicle crossings a day

That is 1.3% of the county's reported daily bridge traffic on 12.9% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 78 crossings a day against 346 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 Hamlin 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 41.9% 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 32.1% of the county's Poor-condition bridge traffic

438th Avenue over BN Railroad, built 1936, carries 200 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 8-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 624 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1910s

1
1920s

2
1930s

6
1940s

3
1950s

7
1960s

4
1970s

8
1980s

3
1990s

8
2000s

8
2010s

7
2020s

5

What this shows Construction peaked in the 1970s, when 8 of the county's bridges still in the inventory were built, which is 12.9% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1978) matches the South Dakota average (1975).

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

The 5 South Dakota counties nearest Hamlin County in number of bridges, with their condition splits. Its 12.9% Poor share is the 3rd-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 Hamlin 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
Hanson County	62	19.4%	71%	9.7%	1978
Hamlin County (this page)	62	41.9%	45.2%	12.9%	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 Hamlin 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 Hamlin 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 26 Fair 28 Poor 8

All bridges (62)

Sort:

Hamlin County Bridge Snapshot

Condition distribution

Hamlin County's Poor-condition bridges carry 624 vehicle crossings a day

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

One structure carries 32.1% of the county's Poor-condition bridge traffic

How Hamlin 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)

459th Avenue

463rd Avenue

446th Avenue

188th Street

450th Avenue

195th St 452nd Ave

459th Avenue

190th Street

463rd Avenue

464th Avenue

SD022

SD028

I029 S

I029 N

I029 S

I029 N

SD028

SD028

I029 S

I029 N

US081

SD028

SD022

464 AVE (FAS 6499)

180th Street

SD028

460th Avenue

SD021

SD028

SD028

459th Avenue

464th Avenue

465th Avenue

463rd Avenue

192nd Street

Bluejay Street

SD028

SD022

189th Street

184th Street

167th Street

462nd Avenue

195th Street

446th Avenue

192nd Street

2nd Avenue

180th Street

180th Street

181st Street

459th Avenue

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