Recreation is a vital part of public health. Recreational activities provide necessary exercise for individuals to control weight problems, strengthen hearts, and provide an emotional release from the day-to-day cares faced in the home and at work. With increasing numbers of middle-class people, the development of the interstate highway system, and the overcrowding of many areas, individuals have sought to obtain their fun through recreational activities that take them into state parks, federal parks, various national forest reserves, and local park areas. Each of these areas, while providing the kind of necessary escape from tension and troubles, also provides an environment highly conducive to the spread of disease and injury. Individuals come from different areas, states, and even countries. They congregate in recreational areas and bring diseases from home. These diseases spread readily within the recreational areas because of existent environmental health problems. The public has increased sharply the number of visits to various recreational areas. In 1950, approximately 110 million people visited state parks. In the 1990s, over 500 million people visited state parks. The National Park Service in 1950 had approximately 25 million people visit the various park areas. In the 1990s, over 125 million people visited national parks. The U.S. Forest Service had approximately 30 million people visited forest service areas in 1950. In the 1990s, about 200 million people visited these areas. In the year 2002, these numbers continued to grow even in spite of proposals to limit the number of people entering National Parks to keep from destroying the environment. Facilities are being torn down and areas are being made off-limits. These figures do not include the millions of individuals who visit local and county park and recreational areas.