The short answer is, yes, drones are banned in US national parks. The main law governing the issue is Policy Memorandum 14-05, issued by the National Park Service (NPS) on June 19, 2014. It was intended as an interim policy, but the NPS web page suggests that it is still in force. Policy Memorandum 14-05 prohibits the launching, landing, and operation of unmanned aerial vehicles on NPS-administered lands and waters. In addition to national parks, these properties include national monuments, national recreation areas, national historic sites, national seashores, and national memorials, among others. The NPS imposes these restrictions to ensure that visitors to its properties as well as native wildlife are not subjected to noise disturbance and to the possibility of physical injury.
NPS guidelines do not apply to all federally-administered and protected properties. Forests are one major exception. The US Forest Service allows drones on its properties but requires that drone operators follow all regular FAA regulations and guidance. Drones must not fly close to wildlife and must not interfere with firefighting operations, manned aircraft or areas with Temporary Flight Restrictions However, these more relaxed rules do not apply to federally-protected areas known as Wilderness Reserves, comprising more than 100 million acres nationwide, some of which fall under the USFS purview. On these properties, drone flights are also strictly banned.
States and localities have their own patchwork of guidelines and restrictions that apply to their park lands. Many states allow drones to operate in their state parks subject to limitations and an approved application for a permit granting the drone operator a special waiver. Finding that information can be difficult and it is not always clear to drone operators how to apply the restrictions stipulated. Even drone operators willing to observe the rules may violate them inadvertently.
Some cities have passed ordinances banning drone flights outright. These measures are meant to discourage reckless drone use, especially in local parks. In reality, the FAA alone governs the nation’s airspace. Whether these measures enjoy the force of law is doubtful. For now, drone operators that obey FAA guidelines are likely well within their rights to fly in any city they like.
That said, drone operators are obligated to know which federal, state and local laws apply to drones and which areas might require a special permit to fly in (or over). The FAA-administered website B4UFLY contains maps where drone flights are expressly prohibited. The maps are not perfect. After a drone landed in the Bolsa Rica bird sanctuary outside Los Angeles earlier this year, it was revealed that the FAA had failed to designate the preserve as a “no drone zone.” The incident has led the FAA to review all of its drone maps to ensure their accuracy.