California holds the record for the most National Parks, boasting nine iconic sites including Yosemite, Joshua Tree, and Death Valley. However, when looking at National Monuments, Arizona takes the lead with 18 distinct monuments managed by the National Park Service and other federal agencies. If you combine all units of the National Park System (which includes parks, monuments, historical sites, and preserves), California remains the overall leader in diversity and quantity of protected areas. Arizona is a close second, particularly dominant in the "monument" category due to its vast stretches of Bureau of Land Management (BLM) land and ancient archaeological sites like Montezuma Castle and Canyon de Chelly. In 2026, these states continue to be the primary hubs for domestic "National Park road trips," with the high concentration of sites making it possible for travelers to visit multiple federally protected landscapes in a single week-long journey through the American West.