County profile · official public datasets

Pennington County, SD

348 public highway bridges tracked in the FHWA National Bridge Inventory: 30.2% rated Good, 62.4% Fair, 7.5% Poor.

348
Public bridges: 30.2%
Good condition: 7.5%
Poor condition

The verdict

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

Pennington County posts a top-quartile lowest Poor-condition share among rated counties in the state across mid-size county bridge inventory.

Top 24%
lowest Poor share in state: 7.5%
Poor-condition share: 348
public highway bridges: 1976
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.

Pennington County Bridge Snapshot

According to the Federal Highway Administration's 2024 National Bridge Inventory, Pennington County ranks #16 of 66 South Dakota counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 7.5%). Pennington County, South Dakota contains 348 public highway bridges. Roughly 30.2% are rated “Good,” 62.4% “Fair,” and 7.5% “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

348

Public highway bridges in Pennington County

Good condition

30.2%

105 of 348 rated 7-9

Fair condition

62.4%

217 of 348 rated 5-6

Poor condition

7.5%

26 of 348 rated 4 or below

In-state Poor-share rank

#16 of 66

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

Condition distribution

Share of 348 NBI-tracked bridges by lowest applicable component rating.

Good

30.2% (105)

Fair

62.4% (217)

Poor

7.5% (26)

Pennington County's Poor-condition bridges carry 12,863 vehicle crossings a day

That is 1.1% of the county's reported daily bridge traffic on 7.5% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 495 crossings a day against 3,274 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 347 of 348 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.

62.9% of Pennington County's bridges have passed the 50-year mark

219 of the 348 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 30.2% 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 36.5% of the county's Poor-condition bridge traffic

CHAPEL LANE over RAPID CK, built 1974, carries 4,700 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 26-bridge count understates how much of the daily burden sits on a single crossing.

Share is of the 12,863 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.

1910s

1
1920s

3
1930s

9
1940s

10
1950s

29
1960s

79
1970s

99
1980s

34
1990s

29
2000s

35
2010s

14
2020s

6

What this shows Construction peaked in the 1970s, when 99 of the county's bridges still in the inventory were built, which is 28.4% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1976) matches the South Dakota average (1975).

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

The 5 South Dakota counties nearest Pennington County in number of bridges, with their condition splits. Its 7.5% Poor share is the 1st-lowest of these 6. Its average build year of 1976 against a peer-group mean of 1978 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 Pennington County and the 5 South Dakota counties closest to it in inventory size
County	Bridges	Good	Fair	Poor	Avg. built
Minnehaha County	393	40.5%	50.1%	9.4%	1985
Pennington County (this page)	348	30.2%	62.4%	7.5%	1976
Brookings County	233	26.6%	50.6%	22.7%	1973
Meade County	215	43.7%	45.6%	10.7%	1979
Lincoln County	207	34.3%	48.3%	17.4%	1973
Grant County	205	35.1%	48.8%	16.1%	1980

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

Similar inventory size

Nearest county inventories outside SD (348 bridges here).

Fillmore County, MN · 348 bridges
Cumberland County, NC · 348 bridges
Mahoning County, OH · 348 bridges
Cumberland County, PA · 348 bridges

Similar average build year

Nearest mean year-built outside SD (1976 here).

Marion County, IN · avg 1976 · 958 bridges
Mohave County, AZ · avg 1976 · 641 bridges
Comanche County, OK · avg 1976 · 593 bridges
Prince George's County, MD · avg 1976 · 576 bridges

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

All 348 Good 105 Fair 217 Poor 26

All bridges (348)

Sort:

TOWNSHIP RD

Good

Over: BOXELDER CK

OWANKA, Pennington, SD

Built 2006 Load: 48.9 t ADT: 15

SWANZEY DRIVE

Good

Over: GRIZZLY BEAR CK

150S200E JCT16A40 KEYSTON, Pennington, SD

Built 1974 Load: 49.0 t ADT: 125

I090 W

Good

Over: E NORTH ST

E NORTH & I 90 INTERCHANG, Pennington, SD

Built 2005 Load: 49.0 t ADT: 16,095

US016 B (SE CONN)

Good

Over: RCP&E RR

0.3E SD79, Pennington, SD

Built 2005 Load: 49.5 t ADT: 11,086

US016 B (SE CONN)

Good

Over: RCP&E RR

0.2 S I 90 INTERCH, Pennington, SD

Built 2005 Load: 49.5 t ADT: 14,488

SD044

Good

Over: RAPID CK

5.9 SE JCT US 385, Pennington, SD

Built 1956 Load: 49.9 t ADT: 3,104

US016AEF

Good

Over: GRIZZLY BEAR CK

AT KEYSTONE, Pennington, SD

Built 1973 Load: 50.0 t ADT: 1,993

BRADSKY ROAD

Good

Over: RAPID CK

3.5 W & 1.3 N CAPUTA, Pennington, SD

Built 2018 Load: 50.3 t ADT: 311

US016A

Good

Over: US016A

1.8 S JCT SD 244, Pennington, SD

Built 1976 Load: 50.7 t ADT: 404

US016 B (SE CONN)

Good

Over: SD044 SD RR (ABAND)

JCT US16B & SD44, Pennington, SD

Built 2002 Load: 53.2 t ADT: 16,648

SD044

Good

Over: RAPID CK

6.4 SE JCT US 385, Pennington, SD

Built 1956 Load: 55.0 t ADT: 3,104

S ROCHFORD

Good

Over: RAPID CK

0.6W 0.1S ROCHFORD, Pennington, SD

Built 2021 Load: 55.5 t ADT: 276

US016A

Good

Over: GRIZZLY BEAR CK

0.7 S JCT SD 244, Pennington, SD

Built 1974 Load: 58.1 t ADT: 582

I090 EB OFF RAMP

Good

Over: CHANNEL CK

2.7 W OF BOX ELDER, Pennington, SD

Built 1994 Load: 58.9 t ADT: 4,974

I190

Good

Over: NORTH ST

North St & I190 INTRCHGE, Pennington, SD

Built 2016 Load: 63.3 t ADT: 10,925

NEW YORK STREET

Good

Over: DRAINAGE DITCH

0.1W OF E. BLVD ON NY ST, Pennington, SD

Built 2001 Load: 69.0 t ADT: 5,250

HUETHER RD

Good

Over: CK

1.0W 5.3N CONATA, Pennington, SD

Built 1981 Load: 72.2 t ADT: 25

SD044

Good

Over: CK

12.5 SE OF SCENIC, Pennington, SD

Built 1983 Load: 74.2 t ADT: 486

LIBERTY BLVD

Good

Over: EAST TRIB BOX ELDER CK

0.3 MI S. I-90 EXIT 67, Pennington, SD

Built 2002 Load: 76.7 t ADT: 2,785

QUINN RD

Good

Over: UNNAMED CK

0.7 N QUINN, Pennington, SD

Built 1990 Load: 80.5 t ADT: 100

SD044

Good

Over: CK

19 SE OF SCENIC, Pennington, SD

Built 1983 Load: 81.8 t ADT: 486

SD044

Good

Over: CK

18.6 SE OF SCENIC, Pennington, SD

Pennington County Bridge Snapshot

Condition distribution

Pennington County's Poor-condition bridges carry 12,863 vehicle crossings a day

62.9% of Pennington County's bridges have passed the 50-year mark

One structure carries 36.5% of the county's Poor-condition bridge traffic

How Pennington 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 (348)

TOWNSHIP RD

SWANZEY DRIVE

I090 W

US016 B (SE CONN)

US016 B (SE CONN)

SD044

US016AEF

BRADSKY ROAD

US016A

US016 B (SE CONN)

SD044

S ROCHFORD

US016A

I090 EB OFF RAMP

I190

NEW YORK STREET

HUETHER RD

SD044

LIBERTY BLVD

QUINN RD

SD044

SD044

SAN MARCO BLVD.

234TH STREET

IDLEHURST LANE

THUNDERHEAD FALLS

TOMAHAWK DR

159TH AVE

HUETHER ROAD

TOWN STREET (US16)

BENNET ROAD

PAULSEN RD

223RD STREET

PAULSEN RD

ROY STREET

THUNDERHEAD FALLS

HAMMERQUIST ROAD

THUNDERHEAD FALLS

COUNTRY ROAD

SUMMERSET DRIVE

THUNDERHEAD FALLS

NORRIS PEAK ROAD

SLATE PRAIRIE ROAD

McCURDY GULCH

THUNDERHEAD FALLS

CHAPEL LANE

THUNDERHEAD FALLS

US385

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