The townsite of Green River, Dakota Territory was platted by the Union Pacific Railroad in 1867.

The Town of Green River was re-incorporated on June 10, 1891 under the laws of the State of Wyoming to remove any ambiguity.

They moved the division point 12 miles (19 km) west, creating the town of Bryan, on the Blacks Fork of the Green River.

[7] Just when Green River was on the verge of becoming a ghost town, Blacks Fork dried up during a drought and the railroad was forced to move the division point back to Green River to ensure adequate water for its steam locomotives.

The mining operation is less expensive for production of soda ash in the United States than the synthetic Solvay process, which predominates in the rest of the world.

With the loss of outflows, highly alkaline water (salt brine) began to evaporate, depositing the beds of trona.

[13] The four mines are run by these companies: The Green River Basin also has large oil shale and natural gas reserves, which remain virtually untouched due to the high cost of extracting the oil from the hard shale formations.

Expansion growth from Halliburton and Exxon, as well as other oil companies, created a mini-boom for Green River and its sister city, Rock Springs.

[16] Every year, on the last full weekend of June, Green River hosts Flaming Gorge Days.

Past musical performances at the festival have included Poison, Tesla, Everclear, Head East, Neal McCoy, REO Speedwagon, Josh Gracin, Chris LeDoux and Trick Pony.

[17] Green River's government consists of a six-member city council, each of whom are elected from one of three wards.

Public education in the City of Green River is provided by Sweetwater County School District #2.

Western Wyoming Community College is located in nearby Rock Springs and maintains an extension center in Green River.

The practice, widely condemned by animal rights groups, has faced protests from citizens and activists.

Despite offers to fund a transition to humane euthanasia methods, city officials have refused to discontinue gas chamber use.