Time in South Dakota Time in South Dakota South Dakota lies in both the Mountain Time Zone and the Central Time Zone. Mountain Time roughly contains the western half of the state, but not all of it. Rapid City is the largest city in the Mountain Time portion of the state. Central Time contains the eastern half of the state and roughly more of the state than the Mountain Time Zone and includes the state capital Pierre and the largest city, Sioux Falls. The 2 zones for South Dakota as given by zone.tab of the IANA time zone database. Columns marked * are from
South Dakota Highway 89 The section of SD 89 from Custer to Sylvan Lake was once part of US 85 Alternate. South Dakota Highway 89 South Dakota Highway 89 (SD 89) is a state highway in the southwestern part of the U.S. state of South Dakota. The highway travels from U.S. Route 18 (US 18) near Minnekahta to SD 87 in Custer State Park. SD 89 is concurrent with US 385 from Pringle to Custer. The portion of the highway from Custer to SD 87 is part of the Peter Norbeck Scenic Byway. SD 89 was established in 1950 from Spearfish to Minnekahta. The