Gillette is a city in and the county seat of Campbell County, Wyoming, United States. The population was estimated at 31,797 as of 1 July 2013. Gillette is centrally located in an area involved with the development of vast quantities of American coal, oil, and coalbed methane gas. The city calls itself the "Energy Capital of the Nation," noting that the state of Wyoming provides nearly 35% of the nation's coal. Over the last decade Gillette saw a population increase of 48% from the 2000 census of 19,646 residents.