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Irr US018 over Slim Butte Ck

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

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

Irr US018 over Slim Butte Ck in Oglala Lakota 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 superstructure, rated 6 (satisfactory condition) on the 0-9 scale.
It was built in 1953, making it 72 years old at the 2025 inventory.
It carries about 1,294 vehicles a day (traffic count year 2024).
Its listed owner is the state highway agency.
It is one of 13 of the 35 inventoried bridges in Oglala Lakota County rated fair (37.1%); 2 (5.7%) 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


Structure	Steel stringer or multi-beam girder
Length	about 118 ft
Location	9 E Fall River Co Line
NBI structure number	000000057096359
Condition class	Fair

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

Bridge	Built	Vehicles/day	Condition
Irr Bia Rte 36 over White Clay Creek	2001	7,551	Good
Irr US018 over Wolf Ck	2006	5,154	Fair
Irr US018 over Ck	2016	3,597	Good
Irr US018 over Ck	2011	3,274	Good
Irr US018 over Cheyenne Ck	2020	3,274	Good
Irr Bia Rte 27 over White River	1985	2,368	Fair