SweetwaterDealer license in Wyoming is about to be introduced. Sweetwater County is a county located in the U.S. state of Wyoming. The region is the largest county in the state. From 2010, the population was 43,806. Its county seat is Green River. Sweetwater County was originally created on December 17, 1867, a county in Dakota Territory. County areas that were previously part of Laramie County. The county was originally named Carter County Judge WA Carter of Fort Bridger. In 1869, the Legislature renamed the newly created Territory of Wyoming County Sweetwater River. Also in 1869, Uinta County was held with the supply of Sweetwater County. Johnson County, originally called Pease County, formed in some parts of Sweetwater County and Carbon County in 1875. In 1884, Sweetwater County lost in Fremont County was created. Sweetwater County lost in Carbon County was created in 1886. At that point, the county reached its current limits with the exception of minor changes in 1909, 1911 and 1951. South Pass City was the county seat from 1867 until 1873. At that time, the county seat was moved to Green River.