Existed: 1929 – present Length 690.2 km | East end: US 212 in Watertown Constructed 1929 | |
 | ||
West end: Montana state line near Camp Crook Major
junctions: US 85 in Buffalo
US 12 in Mobridge
US 83 in Selby
US 281 west of Mellette West end: I-29 / US 81 west of South Shore East end: MN 40 at the Minnesota state line east of Revillo Major cities Watertown, Mobridge, Buffalo, Timber Lake, Hoven, Revillo, Florence, South Shore, Mellette, Bison, Selby Counties Harding County, South Dakota | ||
South Dakota Highway 20 (SD 20) is a state route that largely runs from border to border across the northern part of the U.S. state of South Dakota. It is one of the state's most rural highways.
Contents
Map of SD-20, South Dakota, USA
South Dakota Highway 20 consists of two segments. The longer segment begins at the Montana border west of Camp Crook, and terminates at the junction of U.S. Route 212 (US 212) in Watertown. This segment is just less than 390 miles (630 km) in length. A second segment begins just west of an interchange with Interstate 29 (I-29) and US 81. It continues eastward to the Minnesota border east of Revillo, then becomes Minnesota State Highway 40 (MN 40). This second segment is just over 39 miles (63 km) in length, and the total length of the route is about 429 miles (690 km).
History
South Dakota 20 was implemented in 1929, but it was much shorter. The western terminus was at South Dakota Highway 45 northeast of Faulkton, and terminated in Watertown. Around 1944, the western terminus was moved further west, to U.S. Highway 83.
In the early 1950s, a short extension west was made again, to the town of Akaska. The eastern terminus was moved as well, to U.S. Highway 77 south of Milbank; the extension to the Minnesota border occurred in 1954.
In the late 1960s, the short stub between Akaska and U.S. 83 was redesignated as South Dakota Highway 20 Spur. SD 20 was extended northward along U.S. 83 to U.S. Highway 12, then through Mobridge and across north central and northwest South Dakota, absorbing the alignment of what had been South Dakota Highway 8.