Total bridges
348
Public highway bridges in Pennington County
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.
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.
When Pennington County's bridges were built
348 bridges with a recorded construction year, grouped by decade
- 1910s 1
1910–1919
1 bridges
- 1920s 3
1920–1929
3 bridges
- 1930s 9
1930–1939
9 bridges
- 1940s 10
1940–1949
10 bridges
- 1950s 29
1950–1959
29 bridges
- 1960s
1960–1969
79 bridges
- 1970s
1970–1979
99 bridges
- 1980s 34
1980–1989
34 bridges
- 1990s 29
1990–1999
29 bridges
- 2000s 35
2000–2009
35 bridges
- 2010s 14
2010–2019
14 bridges
- 2020s 6
2020–2029
6 bridges
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.
| 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.
Good-condition bridges (105)
SD044
GoodOver: CK
12.5 SE OF SCENIC, Pennington, SD
Built 1983 Load: 74.2 t ADT: 486
LIBERTY BLVD
GoodOver: 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
GoodOver: UNNAMED CK
0.7 N QUINN, Pennington, SD
Built 1990 Load: 80.5 t ADT: 100
SD044
GoodOver: CK
19 SE OF SCENIC, Pennington, SD
Built 1983 Load: 81.8 t ADT: 486
SD044
GoodOver: CK
18.6 SE OF SCENIC, Pennington, SD
Built 1983 Load: 99.9 t ADT: 486
Read our methodology - how this data is sourced, computed, and verified.
Related
Data sourced from official public datasets. See our methodology for details. Retrieved and formatted by PlainBridges
Every figure on PlainBridges is rendered directly from federal source data, no number is typed in by an editor. This page draws directly on federal source data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. NBI condition categories reflect the latest reported inventory record, not a live safety, closure, or travel decision.