Kemmerer is a city in and the county seat of Lincoln County, Wyoming, United States. The population was 2,415 at the 2020 census. Founded in 1897, the town grew up around the coal mines of the Ham's Fork field. The town was struck by one of the worst mining disasters in Wyoming history in 1923, and in the 2020s it became the site of TerraPower's Natrium reactor, the first utility-scale advanced nuclear power plant to begin construction in the United States.