If you put together all the public lands that Americans can’t actually reach, it amounts to an area more than 10 times the size of Yellowstone National Park.

It sounds difficult to believe, yet that’s exactly what research from onX has shown. Known primarily as a navigation app popular with hunters, the digital mapping company has also been working to improve access to public land.

OnX released a report in 2021 showing that nearly 16.5 million acres of public land around the country can’t actually be reached — not legally, anyway. Many public lands are surrounded by private property, so anyone who tries to visit, including government officials, risks trespassing charges from landowners.