Clearfield is a borough in Clearfield County, Pennsylvania, United States. The population was 6,631 at the 2000 census. It is the county seat of Clearfield County. According to the United States Census Bureau, the borough has a total area of 1.9square miles (4.9Square kilometers), of which, 1.8square miles (4.7Square kilometers) of it is land and 0.1square miles (0.26Square kilometer) of it (3.70%) is water. As of the census of 2000, there were 6,631people, 3,070households, and 1,740families residing in the borough. The population density was 3,649.7people per square mile (1,406.7/Square kilometers). There were 3,326housing units at an average density of 1,830.6per square mile (705.6Square kilometers).