Green River is the County Seat of Sweetwater County and its second largest city. Unlike Rock Springs which grew up as a coal mining town, Green River developed through its relationship with the Union Pacific Railroad. Green River succeeded South Pass as the County Seat in 1872. In the same year, Green River became a Division Point on the Union Pacific Railroad. A large railroad yard and shop facilities were built south of the downtown area and an imposing brick depot eventually replaced the original wood frame building. The historic downtown is located immediately north of the tracks on Railroad Avenue and Flaming Gorge Way. The history of Green River and Sweetwater County is told at the Sweetwater Historical Museum located in the Sweetwater County Courthouse on Flaming Gorge Way.
The City of Green River takes its name from the Green River which flows through the center of the city. The river flows through a broad steep-sided valley with prominent rock formations, known as the "Green River Formation", along either side. "The Nature Art Shop" is a brochure which shows pictures and the locations of these many rock formations including the Palisades, Toll Gate and the "Cliffs of Green River" featured in the paintings by Thomas Moran.
Expedition Island, the Green Belt Nature Area, and the Scotts Bottom Nature Area are found along the river. Expedition Island is found immediately south west of the railroad yards. The island was the point where John Wesley Powell began his expedition down the Green and Colorado Rivers which culminated in his trip through the Grand Canyon. Downstream from Expedition Island on the south bank of the river is the Green Belt Nature Area. This area contains nature paths which run along the edge of the river. Water fowl and other types of birds nest in the tall grass and bushes which grow throughout the area. Further to the south of the southern edge of the river is Scotts Bottom Nature Area. Like the Green Belt, the Scotts Bottom Nature area has paths and interpretive signs which tell of the wildlife which live in this riparian habitat along the edge of the Green River.
The Green River offers excellent fishing for Rainbow and Brown Trout, Kokanee Salmon and Catfish. World-class fishing for Brown, Rainbow Trout, Kokanee Salmon, Macinaw, Small Mouth Bass and Catfish is available at Lake Flaming Gorge, accessible from Wyoming Highway 530.