3. American like to visit the national parks. In 1996, over 250, 000, 000 people visited areas run by the National Park Service. Experts predict that by 2022, 500, 000, 000 people per year will visit the parks. As a result, people are trying to think of ways to protect the parks from the crowds.
The crowding of the parks has caused several problems. One is that there is not enough space for all of the people who want to use the parks. To deal with this problem, national parks may require reservations(预定) months in advance for some spots. The Park Service may also raise entrance fees at these places.
Another problem caused by increased park use is pollution. Some garbage and waste can be cleaned up, and the cleanup can be paid for by increased entrance fees. To cut down on noise pollution and air pollution, officials may decrease the number of cars allowed in parks. If this happens, people may use buses to travel around the parks. Officials may also limit the use of jet﹣skis, snowmobiles (摩托雪橇), motorboats, and sightseeing helicopters and planes.
The parks are also threatened by development that is going on around them. For example, around Yellow Stone Park, many motels (汽车旅馆), golf courses, resorts, and other tourist attractions have been built. Some of these developments affect areas that are used by animals. People will have to learn to agree about ways to protect the parks. If they do not, there will soon be no reason to visit these national treasures.