Clay County's population has grown from 25,227 people in 1940 to 58,999 in 2010. The population increased 15.2% between 2000 and 2010. The City of Moorhead is the most populated city, with 38,065 residents. Person under 18 years of age comprise 22.7% of the county population while persons 65 and over comprise 12.4%.
Clay County maintains a 70.9% rate of home ownership, compared to 74.9% statewide. The poverty rate for Clay County, in 2009, was 13.0%, compared to the state average of 10.9%.
The Bureau of Economic Analysis listed the 2009 Per Capita Personal Income (PCPI) for Clay County at $34,304. The 1999 - 2009 average annual growth rate of PCPI was 4.4% in Clay County, 3.2% for the state and 3.4% for the nation. Clay County is fortunate to have a variety of industries, including agricultural and educational.