There are no U.S. national parks that start with the letter F. Out of the 63 parks that carry the official “National Park” title, none begins with F. The list runs from Acadia to Zion, but the F slot stays empty. That surprises many visitors, since several famous places with F names sit inside the National Park System.

The reason is simple. National parks get their names from the land itself, such as a mountain, a river, a canyon, or a nearby town. Most names start with other letters, like Yellowstone, Glacier, Grand Canyon, and Great Smoky Mountains. Congress picks each name when it creates the park, and no F name has been chosen so far. The name of a park also does not always match its type, because the National Park Service manages more than 400 sites, and only a small share of them hold the “National Park” title.

Some places come close. Fort Sumter National Monument in South Carolina, Fort McHenry National Monument and Historic Shrine in Maryland, and Fort Smith National Historic Site in Arkansas all start with F. Fire Island National Seashore in New York and Florissant Fossil Beds National Monument in Colorado do too. These sites are run by the National Park Service, but they are not national parks. People who search for this list are often looking for one of them.