Cumberland is a home rule-class city in Harlan County, Kentucky, in the United States. The population according to the 2010 Census was 2,2…Cumberland is a home rule-class city in Harlan County, Kentucky, in the United States. The population according to the 2010 Census was 2,237, down from 2,611 at the 2000 census. The city sits at the confluence of Looney Creek and the Poor Fork Cumberland River.