Great Divide Basin

Great Divide Basin
Drainage basin
The Great Divide Basin is an endorheic drainage basin on the Continental Divide in the United States.
Country	United States
State	Wyoming
Region	Red Desert
Part of	Wyoming Basin physiographic province
Location	Sweetwater, Carbon, Fremont counties
- elevation	6,500 ft (2,000 m)
- coordinates	41°0′01″N 107°59′2″W / 41.00028°N 107.98389°W / 41.00028; -107.98389Coordinates: 41°0′01″N 107°59′2″W / 41.00028°N 107.98389°W / 41.00028; -107.98389
Area	3,959 sq mi (10,253.8 km2)
Geology	Marine Upper Cretaceous rocks, continental early Paleogene rocks, lacustrine rocks Eocene (Green River Formation)

The Great Divide Basin or Great Divide Closed Basin is an area of land in Wyoming's Red Desert (United States) where none of the water falling as rain to the ground drains into any ocean, directly or indirectly. It is therefore considered an endorheic basin, and it adjoins the Continental Divide in southern Wyoming. To the west of the basin is the Green River watershed, draining to the Gulf of California/Pacific Ocean; to the east is the North Platte watershed, draining to the Gulf of Mexico/Atlantic Ocean. The basin is very roughly rectangular in shape; the northwest corner is in the Wind River Range near South Pass, about 40 miles southwest of Lander, and the southeast corner is in the Sierra Madre Range near Bridger Pass, about 20 miles southwest of Rawlins.

Although the Great Divide Basin provides a relatively low and easy crossing of the Continental Divide, its aridity and endorheic nature were an obstacle to pioneers during the westward expansion of the United States, and was known as the Saline Plain around the 1870s. Consequently, the Oregon Trail detoured north over South Pass, and the Overland Trail detoured south over Bridger Pass. By contrast, during the construction of the first transcontinental railroad, the Union Pacific was laid directly across the southern part of the basin. (The original railroad map labelled one point along this route as Bridgers Pass, giving rise to the still-common misconception that the railroad followed the Overland Trail.) Roughly the same route across the basin was later taken by the transcontinental highways traversing the region, namely the Lincoln Highway, U.S. 30, and Interstate 80. The basin is also traversed in a north-south direction by U.S. 287 and Wyoming 789. Even today the basin is very sparsely populated, the only incorporated town being Wamsutter, with a population of 451 at the 2010 census.