The increase in trees is due to a number of factors, including conservation and preservation of national parks, responsible tree growing within plantations — which have been planting more trees than they harvest — and the movement of the majority of the population from rural areas to more densely populated areas, such as cities and suburbs. Tree planting efforts begun in the 1950s are paying off and there is more public awareness about the importance of trees and forests. Finally, 63 percent of the forest land in the United States is privately owned, and many landowners are leaving their land intact instead of using it for agriculture or logging (at least partially because many of these activities have shifted overseas