Total bridges
44
Public highway bridges in Douglas County
County profile · official public datasets
Douglas County, SD
44 public highway bridges tracked in the FHWA National Bridge Inventory: 45.5% rated Good, 38.6% Fair, 15.9% Poor.
- 44
- Public bridges
- 45.5%
- Good condition
- 15.9%
- Poor condition
The verdict
According to the Federal Highway Administration's 2024 National Bridge Inventory.
Douglas 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.
- 35th
- of 66 on Poor share
- 15.9%
- Poor-condition share
- 44
- public highway bridges
- 1969
- 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.
Douglas County Bridge Snapshot
According to the Federal Highway Administration's 2024 National Bridge Inventory, Douglas County ranks #35 of 66 South Dakota counties with at least 5 public highway bridges on Poor-condition share (lower share ranks better; currently 15.9%). Douglas County, South Dakota contains 44 public highway bridges. Roughly 45.5% are rated “Good,” 38.6% “Fair,” and 15.9% “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
45.5%
20 of 44 rated 7-9
Fair condition
38.6%
17 of 44 rated 5-6
Poor condition
15.9%
7 of 44 rated 4 or below
In-state Poor-share rank
#35 of 66
Among South Dakota counties with 5+ bridges, lower share ranks better
Condition distribution
Share of 44 NBI-tracked bridges by lowest applicable component rating.
Good 45.5% (20)
Fair 38.6% (17)
Poor 15.9% (7)
Douglas County's Poor-condition bridges carry 1,209 vehicle crossings a day
That is 9.8% of the county's reported daily bridge traffic on 15.9% of its bridges: Poor-condition structures carry less traffic than their share of the inventory. Each Poor bridge averages 173 crossings a day against 353 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 44 of 44 bridges in this county that report an average daily traffic count. Source: FHWA National Bridge Inventory, 2024 release.
50% of Douglas County's bridges have passed the 50-year mark
22 of the 44 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 45.5% 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 48.6% of the county's Poor-condition bridge traffic
IRR US018 over CREEK, built 1961, carries 588 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 7-bridge count understates how much of the daily burden sits on a single crossing.
Share is of the 1,209 daily crossings on Poor-rated bridges that report a traffic count. Source: FHWA National Bridge Inventory, 2024 release.
When Douglas County's bridges were built
44 bridges with a recorded construction year, grouped by decade
- 1910s 1
1910–1919
1 bridges
- 1920s
1920–1929
4 bridges
- 1930s 1
1930–1939
1 bridges
- 1940s
1940–1949
4 bridges
- 1950s 3
1950–1959
3 bridges
- 1960s
1960–1969
7 bridges
- 1970s
1970–1979
6 bridges
- 1980s
1980–1989
9 bridges
- 1990s
1990–1999
5 bridges
- 2000s 2
2000–2009
2 bridges
- 2010s 1
2010–2019
1 bridges
- 2020s 1
2020–2029
1 bridges
What this shows Construction peaked in the 1980s, when 9 of the county's bridges still in the inventory were built, which is 20.5% of those with a recorded year. That cohort is now 35 to 44 years old in the 2024 inventory. Its average build year is 1969, 6 years older than the South Dakota average of 1975.
How Douglas County compares with South Dakota's closest counties by inventory size
The 5 South Dakota counties nearest Douglas County in number of bridges, with their condition splits. Its 15.9% Poor share is the 3rd-lowest of these 6. Its average build year of 1969 against a peer-group mean of 1973 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 |
|---|---|---|---|---|---|
| Corson County | 49 | 32.7% | 57.1% | 10.2% | 1973 |
| Harding County | 49 | 51% | 46.9% | 2% | 1985 |
| Faulk County | 46 | 19.6% | 58.7% | 21.7% | 1966 |
| Douglas County (this page) | 44 | 45.5% | 38.6% | 15.9% | 1969 |
| Hughes County | 40 | 40% | 37.5% | 22.5% | 1978 |
| Marshall County | 39 | 15.4% | 51.3% | 33.3% | 1965 |
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 Douglas 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 Douglas County, both outside South Dakota so the neighborhoods are not the same-state size table above.
Similar inventory size
Nearest county inventories outside SD (44 bridges here).
- Archuleta County, CO · 44 bridges
- Bacon County, GA · 44 bridges
- Pulaski County, GA · 44 bridges
- Rockdale County, GA · 44 bridges
Similar average build year
Nearest mean year-built outside SD (1969 here).
- Cook County, IL · avg 1969 · 1,721 bridges
- Fresno County, CA · avg 1969 · 916 bridges
- Cuyahoga County, OH · avg 1969 · 871 bridges
- Ventura County, CA · avg 1969 · 501 bridges
Source: FHWA National Bridge Inventory, 2024 release. Peers floor at 10 bridges so stub inventories cannot own the match.
Fair-condition bridges (17)
40290 285 ST
FairOver: CK
1.0S 0.9E OF DELMONT, Douglas, SD
Built 1925 Load: 6.6 t ADT: 10
27070 392 AVE
FairOver: CHOTEAU CK
2.3N & 3E OF CORSICA, Douglas, SD
Built 1978 Load: 16.3 t ADT: 25
39510 284 ST
FairOver: CHOTEAU CK
5.9 W. DELMONT, Douglas, SD
Built 1925 Load: 17.4 t ADT: 320
27510 395 AVE
FairOver: CHOTEAU CK
4.9N 3.0E OF ARMOUR, Douglas, SD
Built 1940 Load: 18.7 t ADT: 77
38850 274 ST
FairOver: ANDES CK
1.0S & 0.5W OF CORSICA, Douglas, SD
Built 1991 Load: 19.1 t ADT: 30
38910 282 ST
FairOver: ANDES CK
1.5S 2.9W OF ARMOUR, Douglas, SD
Built 1987 Load: 19.1 t ADT: 10
26960 393 AVE
FairOver: CHOTEAU CK
2.4N 4.0E OF CORSICA, Douglas, SD
Built 1979 Load: 19.1 t ADT: 77
27080 394 AVE
FairOver: CHOTEAU CK
2.2N 5.0E OF CORSICA, Douglas, SD
Built 1983 Load: 19.1 t ADT: 77
28550 398 AVE
FairOver: CK
1.5S 3.0W OF DELMONT, Douglas, SD
Built 1984 Load: 19.1 t ADT: 45
28490 403 AVE
FairOver: CK
0.9S 1.0E OF DELMONT, Douglas, SD
Built 1972 Load: 19.1 t ADT: 25
39470 274 ST
FairOver: CHOTEAU CK
5.6N 2.7E OF ARMOUR, Douglas, SD
Built 1937 Load: 19.6 t ADT: 25
38030 273 ST
FairOver: CK
8.7 W CORSICA, Douglas, SD
Built 1923 Load: 24.5 t ADT: 265
38820 273 ST
FairOver: ANDES CK
0.8 W CORSICA, Douglas, SD
Built 1950 Load: 24.5 t ADT: 526
38830 279 ST
FairOver: ANDES CK
1.5N 3.7W OF ARMOUR, Douglas, SD
Built 1940 Load: 24.5 t ADT: 10
SD044
FairOver: ANDES CK
0.5 W JCT US 281 N, Douglas, SD
Built 1957 Load: 32.9 t ADT: 1,417
US018
FairOver: OAK HOLLOW CK
0.8 W HUTCHINSON CO LINE, Douglas, SD
Built 1961 Load: 33.1 t ADT: 588
IRR US018
FairOver: BRANCH OF CHOTEAU CK
0.1 E CHARLES MIX CO LINE, Douglas, SD
Built 1961 Load: 33.3 t ADT: 588
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.