Clifton is a town in and the county seat of Greenlee County, Arizona, United States, along the San Francisco River. The population of the town was 3,311 at the 2010 census, with a 2017 population estimate of 4,870 by the Arizona Office of Economic Opportunity. It was a site of the Arizona copper mine strike of 1983.Clifton and Morenci are considered to be an economic unit by the Arizona Department of Commerce.