Bridge conditions in Grant County, South Dakota

205 inventoried bridges · 38 rated poor · 2025 National Bridge Inventory

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

Grant County has 38 bridges rated poor out of 205 inventoried, a 18.5% share that puts it well above the national rate of about 7%.

38 of the 205 bridges in Grant County, South Dakota, are rated in poor condition (18.5%) in the 2025 National Bridge Inventory, as of August 20, 2026.
100 bridges (48.8%) are rated good and 67 (32.7%) fair.
The median Grant County bridge was built in 1997.
The busiest poor-rated bridge is 2ND Avenue over BNSF Railroad (built 1914), carrying about 2,560 vehicles a day.

Good 48.8% · Fair 32.7% · Poor 18.5% of 205 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
2ND Avenue over BNSF Railroad	1914	2,560	Poor
W. Milbank St-milb over South Fork Whetstone Rv	1984	696	Poor
147 Street over Ck	1926	100	Poor
147 Street over Ck	1926	100	Poor
163 Street over South Fork Yellow Bank R	1930	98	Poor
480 Avenue over Ck	1969	96	Poor
475 Avenue over Ck	1965	75	Poor
482 Avenue over Whetstone Rv	1978	57	Poor
466 Avenue over Ck	1930	54	Poor
148 Street over Big Sioux Rv	1930	52	Poor
152 Street over Indian Rv	1932	52	Poor
142 Street over Ck	1958	52	Poor
144 Street over North Fork Whetstone Rv	1965	52	Poor
485 Avenue over Ck	1955	52	Poor
161 Street over S Fork Yellow Bank River	1940	52	Poor
161 Street over S Fork Yellow Bank River	1940	52	Poor
151 Street over Big Sioux Rv	1958	45	Poor
156 Street over Ck	1935	40	Poor
481 Avenue over Ck	1930	40	Poor
456 Avenue over Indian River	1960	35	Poor
150 Street over Ck	1925	35	Poor
485 Avenue over North Fork Yellow Bank R	1930	35	Poor
485 Avenue over Ck	1948	35	Poor
485 Avenue over Ck	1950	35	Poor
487 Avenue over North Fork Yellow Bank R	1958	35	Poor
476 Avenue over Ck	1930	27	Poor
165 Street over South Fork Yellow Bank R	1940	26	Poor
469 Avenue over Ck	1930	25	Poor
471 Avenue over Ck	1926	25	Poor
473 Avenue over South Fork Whetstone Rv	1942	25	Poor
473 Avenue over Ck	1936	25	Poor
474 Ave over Ck	1901	25	Poor
483 Avenue over Whetstone Rv	1962	25	Poor
454 Avenue over Indian River	1936	20	Poor
Center Road over Ck	1927	20	Poor
477 Avenue over Ck	1965	18	Poor
474 Avenue over Ck	1926	15	Poor
160 Street over Ck	1991	10	Poor

Busiest bridges in the county

Bridge	Built	Vehicles/day	Condition
Irr I029 over Indian Rv	1976	6,600	Fair
US012 over Whetstone Rv Div Channel	1955	3,765	Fair
Irr I029 S over 146 St	1977	3,650	Fair
Irr I029 N over 146 St	1977	3,650	Good
Irr I029 S over 149 St (fas 6266)	1976	3,650	Fair
Irr I029 N over 149 St (fas 6266)	1976	3,650	Fair
I029 S over 152 St	1977	3,605	Fair
I029 N over 152 St	1976	3,605	Fair
US012 over Whetstone Rv	2003	3,334	Good
2ND Avenue over BNSF Railroad	1914	2,560	Poor

Source: FHWA National Bridge Inventory, 2025. Counts cover inventoried highway bridges over 20 feet; ratings are reported by the state DOT.

Every bridge in Grant County → - all 205, busiest first, each with its own condition record.

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.