Total bridges
233
Public highway bridges in Brookings County
County profile · official public datasets
Brookings County, SD
233 public highway bridges tracked in the FHWA National Bridge Inventory: 26.6% rated Good, 50.6% Fair, 22.7% Poor.
- 233
- Public bridges
- 26.6%
- Good condition
- 22.7%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Brookings County posts a higher-than-median Poor-condition share among rated counties in the state across mid-size county bridge inventory.
- 49th
- of 66 on Poor share
- 22.7%
- Poor-condition share
- 233
- public highway bridges
- 1973
- 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.
Brookings County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Brookings County ranks #49 of 66 South Dakota counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 22.7%). Brookings County, South Dakota contains 233 public highway bridges. Roughly 26.6% are rated “Good,” 50.6% “Fair,” and 22.7% “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
26.6%
62 of 233 rated 7-9
Fair condition
50.6%
118 of 233 rated 5-6
Poor condition
22.7%
53 of 233 rated 4 or below
In-state Poor-share rank
#49 of 66
Among South Dakota counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 233 NBI-tracked bridges by lowest applicable component rating.
Good 26.6% (62)
Fair 50.6% (118)
Poor 22.7% (53)
Brookings County's Poor-condition bridges carry 12,273 vehicle crossings a day
That is 3.9% of the county's reported daily bridge traffic on 22.7% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 232 crossings a day against 355 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 233 of 233 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
57.5% of Brookings County's bridges have passed the 50-year mark
134 of the 233 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 26.6% 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 11% of the county's Poor-condition bridge traffic
WESTERN AVE. over CK, built 1932, carries 1,356 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 53-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 12,273 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Brookings County's bridges were built
233 bridges with a recorded construction year, grouped by decade
- 1900s 2
1900–1909
2 bridges
- 1910s 3
1910–1919
3 bridges
- 1920s 4
1920–1929
4 bridges
- 1930s
1930–1939
25 bridges
- 1940s 6
1940–1949
6 bridges
- 1950s 18
1950–1959
18 bridges
- 1960s
1960–1969
34 bridges
- 1970s
1970–1979
59 bridges
- 1980s 13
1980–1989
13 bridges
- 1990s 18
1990–1999
18 bridges
- 2000s
2000–2009
34 bridges
- 2010s 10
2010–2019
10 bridges
- 2020s 7
2020–2029
7 bridges
What this shows Construction peaked in the 1970s, when 59 of the county's bridges still in the inventory were built, which is 25.3% of those with a recorded year. That cohort is now 45 to 54 years old in the 2024 inventory. Its average build year (1973) matches the South Dakota average (1975).
How Brookings County compares with South Dakota's closest counties by inventory size
The 5 South Dakota counties nearest Brookings County in number of bridges, with their condition splits. Its 22.7% Poor share is the 5th-lowest of these 6. Its average build year of 1973 against a peer-group mean of 1974 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 |
|---|---|---|---|---|---|
| Brookings County (this page) | 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 |
| Spink County | 176 | 13.6% | 52.8% | 33.5% | 1957 |
| Brown County | 170 | 32.9% | 55.3% | 11.8% | 1983 |
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 Brookings 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 Brookings County, both outside South Dakota so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside SD (233 bridges here).
- Pickens County, AL · 233 bridges
- Washington County, IL · 233 bridges
- Lawrence County, MO · 233 bridges
- Oswego County, NY · 233 bridges
Similar average build year
Nearest mean year-built outside SD (1973 here).
- Jefferson County, AL · avg 1973 · 1,068 bridges
- Erie County, NY · avg 1973 · 906 bridges
- Davidson County, TN · avg 1973 · 832 bridges
- Lancaster County, PA · avg 1973 · 801 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Fair-condition bridges (118)
I029
FairOver: CK
4.6 S US 14 INTERCH, Brookings, SD
Built 1966 Load: 44.8 t ADT: 12,240
US014 E
FairOver: BIG SIOUX RV OVERFLOW
2.5 E OF VOLGA, Brookings, SD
Built 1978 Load: 44.9 t ADT: 4,096
485TH AVENUE
FairOver: CK
1.7N & 1W ELKTON, Brookings, SD
Built 1990 Load: 45.1 t ADT: 92
477TH AVENUE
FairOver: CK
6E & 5.4N BROOKINGS, Brookings, SD
Built 2009 Load: 45.2 t ADT: 92
US014 E
FairOver: BIG SIOUX RV OVERFLOW
2.4 E OF VOLGA, Brookings, SD
Built 1978 Load: 45.5 t ADT: 4,096
SD324
FairOver: MEDARY CK OVERFLOW
0.4 E I 29 INTERCH, Brookings, SD
Built 1974 Load: 46.9 t ADT: 1,295
214TH STREET
FairOver: CK
2S & 2.6W BROOKINGS, Brookings, SD
Built 1970 Load: 47.2 t ADT: 63
US014 E
FairOver: NORTH DEER CK OVERFLOW
4.1 E OF VOLGA, Brookings, SD
Built 1979 Load: 48.2 t ADT: 4,096
US014 W
FairOver: BIG SIOUX RV OVERFLOW
2.4 MI EAST OF VOLGA, Brookings, SD
Built 2001 Load: 48.6 t ADT: 4,096
US014 W
FairOver: BIG SIOUX RV
1.9 MI EAST OF VOLGA, Brookings, SD
Built 2001 Load: 49.6 t ADT: 4,096
US014 W
FairOver: NORTH DEER CK OVERFLOW
4.1 MI EAST OF VOLGA, Brookings, SD
Built 2001 Load: 49.9 t ADT: 4,096
SD324
FairOver: MEDARY CK
0.8 E I 29 INTERCH, Brookings, SD
Built 1974 Load: 50.2 t ADT: 1,295
US014 W
FairOver: BIG SIOUX RV OVERFLOW
1.7 MI EAST OF VOLGA, Brookings, SD
Built 2001 Load: 51.2 t ADT: 4,096
US014 W
FairOver: BIG SIOUX RV OVERFLOW
2.5 MI EAST OF VOLGA, Brookings, SD
Built 2001 Load: 51.2 t ADT: 4,096
US014 W
FairOver: NORTH DEER CK
3.9 MI EAST OF VOLGA, Brookings, SD
Built 2001 Load: 54.0 t ADT: 4,096
US014 E
FairOver: NORTH DEER CK
3.9 E OF VOLGA, Brookings, SD
Built 1978 Load: 55.9 t ADT: 4,096
US014 B
FairOver: WEST BR SIX MILE CK
2.5 W I 29 INTERCH, Brookings, SD
Built 1967 Load: 88.9 t ADT: 9,525
I029 NF
FairOver: CK
2 N I29 & SD 324 INTERCH, Brookings, SD
Built 1967 Load: 99.7 t ADT: 410
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.