Clay is a city in northeastern Jefferson County, Alabama, United States. It is part of the Birmingham–Hoover–Cullman Combined Statistical Area in the north-central part of the state. Local government is run by a mayor and city council. Before incorporation on June 6, 2000, it was a census-designated place. The population nearly doubled in the next decade, reaching 9,708 at the 2010 census, as it has attracted commuters to jobs in the urban areas.