Threatened National Parks. Impacts from sources beyond their borders, overcrowding during some parts of the year, air quality issues, invasive species, and even the maintenance backlog in the National Park System all pose threats of varying degrees to some parks.

One of the most critical problems facing U.S. National Parks in 2026 is "Over-tourism" and the resulting environmental degradation. Popular parks like Zion, Arusha, and Yellowstone have seen such a massive surge in visitors that the sheer volume of foot traffic is eroding delicate trails, stressing local wildlife, and overwhelming the "backstage" infrastructure like sewage and water systems. To combat this, many parks have implemented controversial mandatory reservation systems and "timed entry" slots to limit the number of people in the park at any given time. This overcrowding also leads to a decline in the "visitor experience," as narrow canyons and scenic overlooks become congested with crowds, detracting from the natural solitude the parks were designed to provide. Additionally, the National Park Service is currently struggling with a multi-billion-dollar maintenance backlog, where aging roads, bridges, and visitor centers are falling into disrepair due to a lack of sufficient federal funding to keep pace with the record-breaking attendance numbers.