This thesis sets out to explain the establishment and., . protection of United States federal-' heritage '. land, --throughsome 200 years of conflict and `change. ý. It uses concepts,. like preservation, conservation and --exploitation. As US has .- the-- grown in area and population, pressures on land and natural resources have also intensified, particularly at times of external + and -internal strife: wars, the Depression, etc. As the exploitative pressures grew, a counterbalancing response arose from the preservationists. Various federal agencies have a role in protecting heritage land, none more so than the National Park Service since Its founding in 1916. Its achievements and problems, and Its relations with the other agencies, are discussed in some detail. From one point of view, heritage land Is a location for recreation or contemplation. Others regard It as a potential source of exploitable wealth, specially in its timber mineral and water resources. These opposed positions may be understood in terms of a theory that the countervailing forces of land exploitation and land protection were (and are) expressed politically in the conflict and Interdependence of heritage land protection. More recently, environmental problems have arisen at a global level, suggesting that the preservation : exploitation symbiosis is of relevance there as well. It Is possible that large, though comparatively local, environmental issues in the United States could be resolved through the Interplay of local and global politics.