After a year of pining, visitors are overcrowding national parks like Yellowstone and Yosemite

Having sat at home for much of 2020 because of the pandemic, Americans are heading out in droves to national parks like Yellowstone National Park in Wyoming, and Yosemite National Park in California.

Overcrowding in recent weeks has prompted park officials to launch online reservation systems at places like Maine's Acadia National Park, Montana's Glacier National Park, Colorado's Rocky Mountain National Park and Zion Natural Park in Utah. In locations without reservation systems, parkgoers say they've discovering few to no parking spaces, 4-hour wait times to enter and increased litter along park trails.  "This season, national parks are already bustling," the National Park Service said in a statement last month. "Like lots of places you go this year, we may not yet be able to offer the past level of service as we emerge from the ongoing coronavirus pandemic."