National Parks
National Monuments
National Historical Parks, Memorials, and Battlefields
National Recreation Areas, Seashores and Trails
Other Preserves and Protected Areas
... population is spread out with 22.3% under the age of 18, 8.0% from 18 to 24, 31.0% from 25 to 44, 21.9% from 45 to 64, and 16.9% who are 65 years of age or older. Th ...