In the past two years, Karen Weidert, a public health researcher from Berkeley, California, has managed to snag campsites at impossible-to-book spots around California, including the Steep Ravine Cabins in Mount Tamalpais State Park, one of the two hike-in sites at Julia Pfeiffer Burns State Park, and Kirby Cove Campground in Golden Gate National Recreation Area.

To nab those state park campsites in peak season, it took Weidert hours of working the system before she was able to successfully book. She knew reservations opened up six months in advance at 8 a.m. Pacific Time, but even when she was ready to go on the dot, all the sites booked up instantly. “I realized I needed to understand how it worked in order to get a site,” Weidert says.

Look at the numbers and it’s easy to see why popular sites are hard to get. The 2021 North American Camping Report from KOA found that the number of U.S. households that engage in the activity grew by 3.9 million in 2020. More and more people are camping, especially since the pandemic started, yet there hasn’t been major growth in the number of spots available on public land, including state and national parks. Campgrounds within popular destinations, like Grand Canyon, Yellowstone, or Yosemite, book up literally the second they open.

Read the full story (with an Outside+ subscription) on Outside Online.