| State: | ID |
| Type: | SH |
| Route: | 28 |
| Alternate Name: | Sacajawea Historic Byway |
| Map Custom: | yes |
| Map Notes: | SH-28 highlighted in red |
| Maint: | ITD |
| Length Mi: | 135.645 |
| Length Round: | 3 |
| Length Ref: | [1] |
| Direction A: | South |
| Terminus A: | west of Mud Lake |
| Junction: | in Leadore |
| Direction B: | North |
| Terminus B: | in Salmon |
| Previous Type: | SH |
| Previous Route: | 27 |
| Next Type: | SH |
| Next Route: | 29 |
State Highway 28 (SH-28) is a 135.645-longNaN-long state highway in Idaho which runs from Idaho State Highway 33 (SH-33) near Mud Lake to U.S. Route 93 in Salmon. The entire length of the route is designated as the Sacajawea Historic Byway by the state of Idaho.[2]
Idaho State Highway 28 begins at an intersection with ID 33. The route heads northwest before passing the Mud Lake Airport, proceeding to an intersection with State Highway 22. After a long distance, it proceeds through the Lemhi Valley, bending north before curving northwest again for a short distance. The roadway passes the Leadore Airport on its way into Leadore, meeting Idaho State Highway 29 while in the community. Just after exiting the town, the road travels parallel to the Lemhi River for several miles before ending at U.S. Route 93 in the community of Salmon.