Fossil Butte National Monument is near the geographical center of Fossil Basin. The basin itself is located in the extreme southwestern part of Wyoming in Uinta and Lincoln counties, near the Utah-Idaho border (Fig. 2).

The monument is situated about 10 miles west of Kemmerer, Lincoln County, Wyoming (Fig. 3). U.S. Highway 30N runs just south of the monument as does the Union Pacific Railroad line to Oregon. The abandoned town of Fossil is also immediately south of the monument.

The Kemmerer and Sage quadrangles of the United States Geological Survey cover the entire monument and the surrounding area.