State Highway 21 | ||||
|---|---|---|---|---|
 SH-21 highlighted in red | ||||
| Route information | ||||
| Maintained by ITD | ||||
| Length | 130.869 mi[1] (210.613 km) | |||
| Tourist routes |  Ponderosa Pine Scenic Byway | |||
| Major junctions | ||||
| South end |     I-84 / US 20 / US 26 / US 30 in Boise | |||
| North end |  SH-75 in Stanley | |||
| Location | ||||
| Country | United States | |||
| State | Idaho | |||
| Counties | Ada, Boise, Custer | |||
| Highway system | ||||
| ||||
| ||||
State Highway 21 (SH-21), also known as the Ponderosa Pine Scenic Byway,[2] is a state highway in Idaho. It runs from Boise to Stanley, primarily as a two-lane road. With two-thirds of its length in Boise County, it passes by historic Idaho City and the village of Lowman to the western edge of the Sawtooth Mountains, then along their northern boundary to Stanley.
The road is designated as one of Idaho's scenic byways and provides access to Sawtooth National Recreation Area from Boise and the Treasure Valley. It primarily follows the Boise River and its tributary Mores Creek to the Boise Basin and beyond, and then the upper South Fork of the Payette River and a tributary from Lowman to Banner Creek Summit.
- ^ "State Highway 21 Milepoint Log" (PDF). Idaho Transportation Department. May 15, 2015. Archived from the original (PDF) on March 5, 2016. Retrieved October 24, 2015.
- ^ "Ponderosa Pine Scenic Byway". Visit Idaho. Archived from the original on September 6, 2015. Retrieved October 24, 2015.