Analysis of 688 state parks and 41 national parks shows that total trail length in a park has a significant decelerating scaling relationship with park area. Larger parks have much lower trail densities (less trail per acre) than smaller parks. A decelerating scaling pattern is also found when the number of annual visitors is regressed onto park area. Larger parks have fewer visitors per acre of park. Since trails and visitors are major sources of disturbance for many species of wildlife and plants in most reserves, these scaling patterns have important conservation implications.