National Historic Landmarks are nationally significant historic places designated by the Secretary of the Interior because they possess exceptional value or quality in illustrating or interpreting the heritage of the United States. The NHL program draws upon the expertise of National Park Service staff who work to nominate new landmarks and provide assistance to existing landmarks. The Texas Historical Commission reviews and comments on all proposed NHLs in Texas. The National Park Service has designated over 45 sites in Texas as landmarks, scattered across twenty-nine counties. Not surprisingly, San Antonio’s Alamo, Houston’s Apollo Mission Control Center, the Dealey Plaza Historic District in Dallas, and the Texas State Capitol are all among the list of Texas icons that have achieved landmark status.
The National Monuments designation was created under the Antiquities Act of 1906, which authorizes the President to create such monuments on federal land containing historic landmarks, historic or prehistoric structures, or other objects of historic or scientific interest. Congress may also designate landmarks under its own authority. The Texas Historical Commission has no role in the designation of National Monuments. Texas does have one national monument to date – the Alibates Flint Quarries located in the Texas Panhandle. Here, for 12,000 years, people quarried flint for toolmaking.
National Natural Landmarks are also included in this theme category with 20 sites located within the state of Texas. Natural features represented include several highly decorated cave systems exhibiting a variety of rare speleothems, including the Caverns of Sonora and Boerne's Cave Without a Name. Spectacular places such as Palo Duro Canyon State Park and rare one like Odessa's Meteor Crater are also recognized on this list. Ownership of these sites is as diverse as the features represented and include U.S. Fish and Wildlife Service, state parks and private organizations and individuals.