National Historic Sites, National Historic Parks, National Memorials, and certain other areas listed in the National Park system are historic landmarks of national importance that are highly protected already, often before the inauguration of the NHL program in 1960. There are 20 of these in New York State. The legislation establishing the National Historic Landmark program does not prevent these from being designated, but in practice these are not often named NHLs "per se", due to administrative costs of their nomination and to the low preservation value of designating them.