[citation needed] The portion of the highway from Custer to SD 87 is part of the Peter Norbeck Scenic Byway.

The triple concurrency lasts until entering downtown Custer where SD 89 leaves the two and joins US 16A for under a mile before turning north on the east side of Custer.

The section from SD 87 to Spearfish was redesignated as US 14 Alternate and U.S. Forest Service roads.

The section of SD 89 from Custer to Sylvan Lake was once part of US 85 Alternate and replaced in December 1952.

[3] Media related to South Dakota Highway 89 at Wikimedia Commons