The next time you’re out in the wild, enjoying our parks and state and federal lands, spend a moment in gratitude for the often unseen and unglamorous work that makes your visit possible. And it might just be one of your friends or neighbors you have to thank for the smooth trails you walk or the trash-free landscape you photograph. The National Park Service, with an unfunded maintenance backlog of almost $12 billion, relies on a lot of volunteers to maintain trails and help make visitors’ experience pleasant. Many state and local parks are also chronically underfunded and reliant on volunteers.