Bridge conditions in Brown County, South Dakota
170 inventoried bridges · 20 rated poor · 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
Brown County has 20 bridges rated poor out of 170 inventoried, a 11.8% share that puts it well above the national rate of about 7%.
- 20 of the 170 bridges in Brown County, South Dakota, are rated in poor condition (11.8%) in the 2025 National Bridge Inventory, as of .
- 55 bridges (32.4%) are rated good and 95 (55.9%) fair.
- The median Brown County bridge was built in 1990.
- The busiest poor-rated bridge is US012 over Moccasin Ck (built 1954), carrying about 21,635 vehicles a day.
Good 32.4% · Fair 55.9% · Poor 11.8% of 170 bridges
Bridges rated poor
Every bridge in the county with a poor rating, busiest first. Poor means a major component is rated 4 or lower on FHWA's 0-9 scale; it is a repair flag, not a closure notice.
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US012 over Moccasin Ck | 1954 | 21,635 | Poor |
| US281 over Elm Rv | 1959 | 3,041 | Poor |
| 10TH Avenue SE over Moccasin Creek | 1974 | 2,069 | Poor |
| 134TH Street over Creek | 1930 | 1,400 | Poor |
| 8TH Avenue SE over Moccasin Creek | 1976 | 500 | Poor |
| 396TH Avenue over James River | 1957 | 252 | Poor |
| 373RD Avenue over Snake Creek | 1929 | 98 | Poor |
| 375TH Avenue over Willow Creek | 1968 | 98 | Poor |
| 383RD Avenue over Creek | 1930 | 98 | Poor |
| 135TH Street over Foot Creek | 1977 | 98 | Poor |
| 397TH Avenue over Mud Creek | 1930 | 98 | Poor |
| 398TH Avenue over Mud Creek | 1915 | 98 | Poor |
| 125TH Street over James River | 1920 | 98 | Poor |
| 143RD Street over Mud Creek | 1935 | 98 | Poor |
| 103RD Street over James River | 1900 | 98 | Poor |
| 405TH Avenue over Creek | 1935 | 98 | Poor |
| 133RD Street over Creek | 1935 | 98 | Poor |
| 133RD Street over Creek | 1935 | 98 | Poor |
| 123RD Street over Foot Creek | 1932 | 35 | Poor |
| 102ND Street over Elm Lake | 1935 | 33 | Poor |
Busiest bridges in the county
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US012 over Moccasin Ck | 1954 | 21,635 | Poor |
| Second Street over First Ave NW | 2003 | 11,055 | Fair |
| Second Street over Burlington Northern RR | 2003 | 11,055 | Fair |
| Second Street over Railroad Ave SW | 2003 | 11,055 | Fair |
| 3RD Avenue SE over Moccasin Creek | 2019 | 5,087 | Good |
| US281 over BNSF Railroad | 2001 | 4,468 | Fair |
| US281 over Foot Ck | 1971 | 3,968 | Fair |
| Roosevelt Street N over Moccasin Creek | 1995 | 3,845 | Fair |
| Melgaard Road over Moccasin Ck | 1990 | 3,600 | Good |
| US012 over Antelope Ck | 1972 | 3,468 | Fair |
Source: FHWA National Bridge Inventory, 2025. Counts cover inventoried highway bridges over 20 feet; ratings are reported by the state DOT.
All of South Dakota: South Dakota bridge conditions by county · every download on the data page.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.