South Dakota has 5,883 bridges on public roads, according to the FHWA National Bridge Inventory. Of those, 945 are rated in poor condition — a rate of 16.1% — 140% above the national average of 6.7%. Another 2,900 are in fair condition, while 2,038 are in good condition.
Use the interactive South Dakota bridge map below to explore every bridge, color-coded by condition. Click any cluster to zoom in, then click an individual bridge for its route, structural ratings, year built, daily traffic, and last inspection date. Filter by condition using the checkboxes, or switch to satellite view to see bridges from above. For a national comparison, see the full US bridges interactive map.
South Dakota Bridge Conditions by the Numbers
- 5,883 total bridges on public roads in South Dakota
- 945 in poor condition (16.1%) — above the national average of 6.7%
- 2,900 in fair condition (49.3%)
- 2,038 in good condition (34.6%)
- Oldest bridge in the inventory: 374TH AVENUE, built 1900
Oldest Bridges in South Dakota
The oldest bridges in South Dakota date back to the 1900s. The ten oldest South Dakota bridges still in the national inventory:
| Route / Facility | Crosses | Year Built | Condition |
|---|---|---|---|
| 374TH AVENUE | SAND CREEK | 1900 | Fair |
| 196TH STREET | PEARL CREEK | 1900 | Fair |
| 215TH STREET | BIG SIOUX RV | 1900 | Poor |
| 103RD STREET | JAMES RIVER | 1900 | Poor |
| 46080 314 ST. | CLAY CK DITCH | 1900 | Poor |
| 40401 – 298TH ST | DRY CHOTEAU CREEK | 1901 | Fair |
| 156 ST | CK | 1901 | Fair |
| 474 AVE | CK | 1901 | Poor |
| ELMORE RD | SPEARFISH CK | 1901 | Poor |
| 427 AVE | ROCK CK | 1901 | Poor |
Most Concerning South Dakota Bridges: Poor Condition and High Traffic
The bridges of greatest concern combine a poor structural rating with high daily traffic loads. These South Dakota bridges carry the most vehicles per day while rated in poor condition:
| Route / Facility | Crosses | Daily Traffic | Year Built | Deck | Superstructure | Substructure |
|---|---|---|---|---|---|---|
| US012 | MOCCASIN CK | 21,635 vehicles/day | 1954 | Poor (4) | Poor (4) | Fair (5) |
| 49TH STREET | BIG SIOUX RIVER | 13,800 vehicles/day | 1979 | Poor (4) | Poor (4) | Fair (5) |
| S. CLIFF AVENUE | BIG SIOUX RIVER | 9,363 vehicles/day | 1986 | Poor (4) | Satisfactory (6) | Fair (5) |
| I090 W | SD038 | 8,815 vehicles/day | 1989 | Poor (4) | Satisfactory (6) | Satisfactory (6) |
| I029 N | 302 ST (FAS 6372) | 8,020 vehicles/day | 1960 | Satisfactory (6) | Satisfactory (6) | Poor (4) |
How South Dakota Bridge Conditions Are Assessed
Bridge condition in the NBI is determined by ratings of three structural components — deck, superstructure, and substructure — on a scale of 0 (failed) to 9 (excellent). A bridge is classified as good when all three components score 7 or above. It is classified as poor when any component scores 4 or below. Ratings of 5 or 6 on any component with no component below 5 result in a fair classification. SDDOT coordinates inspections across South Dakota in line with FHWA standards, with most bridges inspected on a 24-month cycle.
Frequently Asked Questions
How many bridges in South Dakota are in poor condition?
945 of South Dakota’s 5,883 bridges are currently rated in poor condition by the FHWA National Bridge Inventory, a rate of 16.1%.
What is the oldest bridge in
The oldest bridge recorded in South Dakota’s NBI inventory is 374TH AVENUE, built in 1900.
What does a poor bridge rating mean?
A poor rating means at least one of a bridge’s three key structural components — deck, superstructure, or substructure — has been rated 4 or below on the NBI 0-9 scale. A rating of 4 is defined as “poor condition,” and ratings of 3, 2, 1, or 0 indicate increasingly serious deterioration. Poor-rated bridges are not necessarily unsafe or closed, but they require priority attention and monitoring.
View all 624,000+ US bridges on the national interactive map
Compare with neighboring states: Iowa bridges map | Minnesota bridges map | Montana bridges map | Nebraska bridges map | North Dakota bridges map | Wyoming bridges map
