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450TH Avenue over Little Minnesota River

Roberts County, South Dakota · rated Poor in the 2025 National Bridge Inventory

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

450TH Avenue over Little Minnesota River in Roberts County, South Dakota, is rated in poor condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the substructure, rated 4 (poor condition) on the 0-9 scale.
It was built in 1950, making it 75 years old at the 2025 inventory.
It carries about 35 vehicles a day (traffic count year 2022).
Its listed owner is the county highway agency.
It is one of 40 of the 158 inventoried bridges in Roberts County rated poor (25.3%); 40 (25.3%) are rated poor.
A poor rating means at least one major component - deck, superstructure, or substructure - is rated 4 or lower on FHWA's 0-9 scale. It does not by itself mean the bridge is unsafe; bridges judged unsafe are closed or load-restricted by their owners.

Component ratings


Structure	Timber stringer or multi-beam girder
Length	about 23 ft
Location	5W & 1N of Claire City
NBI structure number	000000055010046
Condition class	Poor

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

Bridge	Built	Vehicles/day	Condition
Irr SD010 over Ck	2019	7,072	Good
Irr SD010 over Ck	1979	6,275	Fair
458TH Avenue over Creek	1941	5,850	Fair
458TH Avenue over Creek	1941	5,850	Fair
459TH Avenue over Creek	1941	5,850	Good
Irr I029 over Big Spring Ck	1978	5,340	Fair