Business Loop I-90 - Oacoma and Chamberlain

This 7.4 mile route of Business Loop I-90 begins at Exit 260 and Dougan Avenue at the town of Oacoma. Overtaking Highway 16 parallel to the freeway, the business route passes by a number of services including Al’s Oasis en route to the American Legion Memorial (Chamberlain-Oacoma) Bridge across Lake Francis Case of the Missouri River. East into Brule County, Business Loop I-90 enters the Chamberlain city center with it combines with South Dakota 50 along King Street. The pair curve southward and expand into a four-lane boulevard to Sorensen Drive. The route ends south of there as SD 50 east commences a 6.7 mile overlap with Interstate 90 east from Exit 265.

The Chamberlain-Oacoma Bridge opened to traffic on September 25, 1925. Due to the construction of the Fort Randall Dam, the span was relocated and expanded in 1953 to accommodate the creation of Lake Francis Case. Dedicated on December 7, 1953, the bridge has five through truss spans in each direction, connected to the west banks of the Missouri by a long causeway. The crossing was added to National Register of Historic Places in 1995 and refurbished in 2011-12 (Chamberlain-Oacoma Area Chamber of Commerce, 2018).