Total bridges
25
Public highway bridges in Buffalo County
County profile · official public datasets
Buffalo County, SD
25 public highway bridges tracked in the FHWA National Bridge Inventory: 32% rated Good, 64% Fair, 4% Poor.
- 25
- Public bridges
- 32%
- Good condition
- 4%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Buffalo County posts a top-quartile lowest Poor-condition share among rated counties in the state across rated county bridge inventory.
- Top 12%
- lowest Poor share in state
- 4%
- Poor-condition share
- 25
- 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.
Buffalo County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Buffalo County ranks #8 of 66 South Dakota counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 4%). Buffalo County, South Dakota contains 25 public highway bridges. Roughly 32% are rated “Good,” 64% “Fair,” and 4% “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
32%
8 of 25 rated 7-9
Fair condition
64%
16 of 25 rated 5-6
Poor condition
4%
1 of 25 rated 4 or below
In-state Poor-share rank
#8 of 66
Among South Dakota counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 25 NBI-tracked bridges by lowest applicable component rating.
Good 32% (8)
Fair 64% (16)
Poor 4% (1)
Buffalo County's Poor-condition bridges carry 55 vehicle crossings a day
That is 0.4% of the county's reported daily bridge traffic on 4% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 55 crossings a day against 650 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 25 of 25 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
48% of Buffalo County's bridges have passed the 50-year mark
12 of the 25 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 32% 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 100% of the county's Poor-condition bridge traffic
355th Avenue over Crow Creek, built 1975, carries 55 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 1-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 55 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Buffalo County's bridges were built
25 bridges with a recorded construction year, grouped by decade
- 1950s
1950–1959
4 bridges
- 1960s
1960–1969
6 bridges
- 1970s
1970–1979
7 bridges
- 1980s 2
1980–1989
2 bridges
- 1990s
1990–1999
4 bridges
- 2010s 2
2010–2019
2 bridges
What this shows Construction peaked in the 1970s, when 7 of the county's bridges still in the inventory were built, which is 28% 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 Buffalo County compares with South Dakota's closest counties by inventory size
The 5 South Dakota counties nearest Buffalo County in number of bridges, with their condition splits. Its 4% Poor share is the 2nd-lowest of these 6. Its average build year of 1976 against a peer-group mean of 1981 is 5 years older.
Showing the 5 closest of 65 South Dakota counties eligible for comparison.
| County | Bridges | Good | Fair | Poor | Avg. built |
|---|---|---|---|---|---|
| Dewey County | 28 | 57.1% | 28.6% | 14.3% | 1986 |
| Mellette County | 28 | 32.1% | 60.7% | 7.1% | 1980 |
| Buffalo County (this page) | 25 | 32% | 64% | 4% | 1976 |
| Potter County | 24 | 54.2% | 45.8% | 0% | 1981 |
| Todd County | 24 | 41.7% | 29.2% | 29.2% | 1986 |
| Hyde County | 23 | 34.8% | 39.1% | 26.1% | 1974 |
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 Buffalo 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 Buffalo County, both outside South Dakota so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside SD (25 bridges here).
- Kodiak Island County, AK · 25 bridges
- Schley County, GA · 25 bridges
- Lane County, KS · 25 bridges
- Benzie County, MI · 25 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.
Fair-condition bridges (16)
OLD FT THOMPSON RD
FairOver: SOLDIER CREEK
1 Mi. So. of Ft. Thompson, Buffalo, SD
Built 1973 Load: 20.7 t ADT: 50
STATE HIGHWAY 47
FairOver: BIG BEND DAM SPILLWAY
1 Mi. So. of Ft. Thompson, Buffalo, SD
Built 1963 Load: 22.4 t ADT: 676
IRR SD047
FairOver: SOLDIER CK
0.3 NE BIG BEND DAM, Buffalo, SD
Built 1963 Load: 24.2 t ADT: 865
221st Street
FairOver: Elm Creek
10N & 13W of Gann Valley, Buffalo, SD
Built 1975 Load: 24.5 t ADT: 41
349th Avenue
FairOver: Elm Creek
11.0W & 6.8N Gann Valley, Buffalo, SD
Built 1975 Load: 24.5 t ADT: 55
225th Street
FairOver: Elm Creek
6N & 10.6W of Gann Valley, Buffalo, SD
Built 1975 Load: 24.5 t ADT: 41
350th Avenue
FairOver: Crow Creek
9.5W & 3.4S Gann Valley, Buffalo, SD
Built 1975 Load: 24.5 t ADT: 41
Yellow Dog Hill Rd
FairOver: Crow Creek
3S & 11.4W of Gann Valley, Buffalo, SD
Built 1963 Load: 26.0 t ADT: 40
SD045
FairOver: CK
2.8 S JCT SD 34, Buffalo, SD
Built 1960 Load: 27.4 t ADT: 773
SD045
FairOver: BR CROW CK
1.8 N JCT SD 34, Buffalo, SD
Built 1958 Load: 28.1 t ADT: 503
SD045
FairOver: CROW CK
2.2 N BRULE CO LINE, Buffalo, SD
Built 1960 Load: 29.9 t ADT: 971
SD045
FairOver: CROW CK
0.6 S JCT SD 34, Buffalo, SD
Built 1958 Load: 33.5 t ADT: 773
IRR SD050
FairOver: WOLF CK
6.1 S JCT SD 34, Buffalo, SD
Built 1954 Load: 35.3 t ADT: 954
IRR BIA RTE 2
FairOver: CROW CREEK
3.4 KM NW OF SHELBY, Buffalo, SD
Built 1973 Load: 36.2 t ADT: 178
IRR BIA RTE 202
FairOver: SMITH CREEK
0.8 KM S OF SHELBY, Buffalo, SD
Built 1983 Load: 36.5 t ADT: 147
IRR SD034
FairOver: EAST FORK SOLDIER CK
7.3 S HYDE CO LINE, Buffalo, SD
Built 1962 Load: 82.1 t ADT: 874
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.