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Bridge conditions in Brookings County, South Dakota

232 inventoried bridges · 53 rated poor · 2025 National Bridge Inventory

United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled August 20, 2026

About one in 4 bridges in Brookings County is rated in poor condition: 53 of 232 on the federal inventory, one of the higher shares in South Dakota.

53 of the 232 bridges in Brookings County, South Dakota, are rated in poor condition (22.8%) in the 2025 National Bridge Inventory, as of August 20, 2026.
64 bridges (27.6%) are rated good and 115 (49.6%) fair.
The median Brookings County bridge was built in 1970.
The busiest poor-rated bridge is 470TH Avenue over Big Sioux Rv (built 1930), carrying about 1,330 vehicles a day.

Good 27.6% · Fair 49.6% · Poor 22.8% of 232 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
470TH Avenue over Big Sioux Rv	1930	1,330	Poor
471ST Avenue over Ck	1925	1,305	Poor
SD013 over Medary Ck	1938	1,275	Poor
471ST Avenue over Br North Deer Ck	1925	1,163	Poor
478TH Avenue over Ck	1950	1,159	Poor
478TH Avenue over Deer Ck	1950	712	Poor
216TH Street over Ck	1935	597	Poor
471ST Street over North Deer Ck	1925	462	Poor
486TH Avenue over Spring Creek	1950	361	Poor
197TH Street over Ck	1974	345	Poor
464TH Avenue over Ck	1950	241	Poor
486TH Avenue over Ck	1961	175	Poor
485TH Avenue over Ck	1950	139	Poor
482ND Avenue over Ck	1973	137	Poor
200TH Street over Sixmile Ck	1966	127	Poor
219TH Street over Ck	1977	108	Poor
209TH Street over Six Mile Ck	1967	99	Poor
202ND Street over Big Sioux Rv	1970	92	Poor
210TH Street over Big Sioux Rv	1907	92	Poor
199TH Street over Big Sioux Rv	1970	92	Poor
212TH Street over Ck	1930	92	Poor
468TH Avenue over Ck	1930	92	Poor
205TH Street over North Deer Ck	1930	92	Poor
470TH Avenue over Ck	1930	92	Poor
472ND Avenue over Medary Ck	1910	92	Poor
196TH Street over Br of North Deer Ck	1940	92	Poor
473RD Avenue over Br North Deer Ck	1930	92	Poor
473RD Avenue over Ck	1977	92	Poor
206TH Street over Sixmile Ck	1940	92	Poor
475TH Avenue over Medary Ck	1930	92	Poor
205TH Street over Six Mile Ck	1930	92	Poor
476TH Avenue over Six Mile Ck	1950	92	Poor
203 A Street over Six Mile Ck	1940	92	Poor
477TH Avenue over Deer Ck	1930	92	Poor
477TH Avenue over Medary Ck	1968	92	Poor
479TH Avenue over Ck	1930	92	Poor
479TH Avenue over Ck	1920	92	Poor
209TH Street over Ck	1913	92	Poor
210TH Street over Ck	1930	92	Poor
220TH Street over Ck	1941	92	Poor
487TH Avenue over Ck	1993	92	Poor
482ND Avenue over Ck	1950	89	Poor
207TH Street over Ck	1974	75	Poor
207TH Street over Ck	1950	65	Poor
207TH Street over Ck	1950	65	Poor
214TH Street over Big Sioux Rv	1962	64	Poor
214TH Street over Ck	1962	64	Poor
215TH Street over Big Sioux Rv	1900	63	Poor
214TH Street over Ck	1974	63	Poor
213TH Street over Ck	1930	50	Poor
482ND Avenue over Medary Creek	1975	45	Poor
207TH Street over North Deer Ck	1958	32	Poor
219TH Street over Ck	1930	19	Poor

Busiest bridges in the county

Bridge	Built	Vehicles/day	Condition
I029 over Ck	1966	12,240	Fair
I029 over Ck	1966	12,240	Fair
I029 over Ck	1970	9,960	Fair
I029 over Ck	1970	9,960	Fair
I029 over Br Six Mile Ck	1970	9,960	Fair
US014 B over West Br Six Mile Ck	1967	9,030	Fair
US014 B over Six Mile Ck	1967	9,030	Fair
US014 B over East Br Six Mile Ck	1968	8,276	Fair
I029 S over Medary Ck	1966	7,985	Fair
I029 N over Medary Ck	1966	7,985	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.