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400TH Avenue over Mud Creek

Brown County, South Dakota · rated Fair in the 2025 National Bridge Inventory

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

400TH Avenue over Mud Creek in Brown County, South Dakota, is rated in fair condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the deck, rated 6 (satisfactory condition) on the 0-9 scale.
It was built in 1956, making it 69 years old at the 2025 inventory.
It carries about 46 vehicles a day (traffic count year 2022).
Its listed owner is the county highway agency.
It is one of 95 of the 170 inventoried bridges in Brown County rated fair (55.9%); 20 (11.8%) are rated poor.
A fair rating means the lowest-rated major component scores 5 or 6 on FHWA's 0-9 scale: some deterioration or minor section loss, but the structure is sound. It is the middle class, not a warning.

Component ratings

Source: FHWA National Bridge Inventory, 2025 data as reported by the South Dakota department of transportation.

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