Forestland comprised 18,771,000 acres (7,596,000 hectares), more than 50% of the state's total land area, in 2002. Of that total, 18,373,000 acres (7,435,000 hectares) were commercial timberland. The southwest and central plains, the state's timber belt, constitute one of the most concentrated sources of yellow pine in the US. Lumber production in 2002 totaled 2.6 billion board feet, fifth in the US. Two national forests in Arkansas covered a total of 3,540,000 acres (1,432,638 hectares) in 2001.