County profile · official public datasets

Spink County, SD

176 public highway bridges tracked in the FHWA National Bridge Inventory: 13.6% rated Good, 52.8% Fair, 33.5% Poor.

176
Public bridges: 13.6%
Good condition: 33.5%
Poor condition

The verdict

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

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

64th
of 66 on Poor share: 33.5%
Poor-condition share: 176
public highway bridges: 1957
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.

Spink County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Spink County ranks #64 of 66 South Dakota counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 33.5%). Spink County, South Dakota contains 176 public highway bridges. Roughly 13.6% are rated “Good,” 52.8% “Fair,” and 33.5% “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

176

Public highway bridges in Spink County

Good condition

13.6%

24 of 176 rated 7-9

Fair condition

52.8%

93 of 176 rated 5-6

Poor condition

33.5%

59 of 176 rated 4 or below

In-state Poor-share rank

#64 of 66

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

Condition distribution

Share of 176 NBI-tracked bridges by lowest applicable component rating.

Good

13.6% (24)

Fair

52.8% (93)

Poor

33.5% (59)

Spink County's Poor-condition bridges carry 3,295 vehicle crossings a day

That is 9.1% of the county's reported daily bridge traffic on 33.5% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 56 crossings a day against 152 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 176 of 176 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

73.9% of Spink County's bridges have passed the 50-year mark

130 of the 176 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 13.6% 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 13.5% of the county's Poor-condition bridge traffic

SD037 over CK, built 1958, carries 446 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 59-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 3,295 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1900s

5
1910s

9
1920s

6
1930s

41
1940s

15
1950s

30
1960s

21
1970s

11
1980s

9
1990s

10
2000s

6
2010s

11
2020s

2

What this shows Construction peaked in the 1930s, when 41 of the county's bridges still in the inventory were built, which is 23.3% of those with a recorded year. That cohort is now 85 to 94 years old in the 2024 inventory. Its average build year is 1957, 18 years older than the South Dakota average of 1975.

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

The 5 South Dakota counties nearest Spink County in number of bridges, with their condition splits. Its 33.5% Poor share is the 5th-lowest of these 6. Its average build year of 1957 against a peer-group mean of 1971 is 14 years older.

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

Bridge inventory size and condition shares for Spink County and the 5 South Dakota counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Spink County (this page)	176	13.6%	52.8%	33.5%	1957
Brown County	170	32.9%	55.3%	11.8%	1983
Union County	170	31.2%	49.4%	19.4%	1975
Hutchinson County	161	32.9%	50.9%	16.1%	1974
Roberts County	157	22.9%	52.9%	24.2%	1970
Beadle County	152	19.1%	47.4%	33.6%	1955

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

Similar inventory size

Nearest county inventories outside SD (176 bridges here).

Des Moines County, IA · 176 bridges
Perry County, KY · 176 bridges
Winston County, MS · 176 bridges
Paulding County, OH · 176 bridges

Similar average build year

Nearest mean year-built outside SD (1957 here).

Essex County, MA · avg 1957 · 395 bridges
Labette County, KS · avg 1957 · 349 bridges
Greenwood County, KS · avg 1957 · 235 bridges
Greer County, OK · avg 1957 · 230 bridges

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

All 176 Good 24 Fair 93 Poor 59

Good-condition bridges (24)

Sort:

Spink County Bridge Snapshot

Condition distribution

Spink County's Poor-condition bridges carry 3,295 vehicle crossings a day

73.9% of Spink County's bridges have passed the 50-year mark

One structure carries 13.5% of the county's Poor-condition bridge traffic

How Spink 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 (24)

164TH ST

183RD ST

378TH AVE

188TH ST

156TH ST

Town Street

156TH ST

173RD SREET

185TH STREET

154TH STREET

181st Street

164TH ST

170TH ST

404TH AVE

151ST ST

396TH AVE

152ND ST

187 ST

SD020

US212

161ST STREET

162ND ST

398TH AVE

SD028

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