With only 18 percent of total land area, the 20 states that make up the U.S. North support 32 percent of the Nation’s timberland (forest land that is sufficiently productive and sufficiently accessible to produce commercial crops of wood and that is not otherwise restricted from timber harvest by policy or legislation such as designated wilderness or parks).   In the last century, northern forest land increased from 134 to 172 million acres (Fig. 2) while total U.S. forest land remained essentially unchanged. This trend is attributable to a historical pattern of forest harvest, land clearing, farming, farm abandonment, and urbanization that continues to exert influence today.