| Title | Author |
|---|---|
| Simpson, Milward | Wyoming State Archives |
| Simpson, Milward - interview | Wyoming State Archives |
| Simpson, Milward and the death penalty | Robin Everett |
| Simpson’s Hollow | WyoHistory.org |
| Simpson’s Hollow | |
| Site of the Wagon Box Fight | |
| Sixth Crossing of the Sweetwater, Oregon Trail historic site | WyoHistory.org |
| Smith, Alfred E. | Rebecca Hein |
| Smith, Nels | Wyoming State Archives |
| Snodderly, Quintina, Oregon Trail Grave of | WyoHistory.org |