On August 25, 1916, President Woodrow Wilson signed the "Organic Act" creating the National Park Service, a federal bureau in the Department of the Interior responsible for maintaining national parks and monuments that were then managed by the department. The National Park System has since expanded to 431 units (often referred to as parks), more than 150 related areas, and numerous programs that assist in conserving the nation's natural and cultural heritage for the benefit of current and future generations.
The National Park Service manages 431 individual units covering more than 85 million acres in all 50 states, the District of Columbia, and US territories. While there are at least 19 naming designations, these units are commonly referred to as "parks." Multiple parks may be managed together as an administrative unit within the National Park Service. (See more information about recent changes in the National Park System and park anniversaries.)
Blue Ridge Parkway, North Carolina and Virginia 
George Washington Memorial Parkway, District of Columbia, Maryland, and Virginia 
John D. Rockefeller, Jr. Memorial Parkway, Wyoming 
Natchez Trace Parkway, Mississippi
Related areas are linked in importance and purpose to places managed directly by the National Park Service by preserving important segments of the nation's natural and cultural heritage. They are designated by acts of Congress or by the Secretary of the Interior (affiliated areas). The majority of related areas are not units of the National Park Service and are managed by other government agencies or non-government organizations and landowners. The National Park Service is involved in related areas by directly managing the entire or sections of a related area, or by providing technical or financial assistance.
Aleutian World War II National Historic Area, Alaska 
American Memorial Park, Saipan 
Benjamin Franklin National Memorial, Pennsylvania 
Chicago Portage National Historic Site, Illinois 
Chimney Rock National Historic Site, Nebraska 
Eutaw Springs Battlefield, South Carolina 
Fallen Timbers Battlefield and Fort Miamis National Historic Site, Ohio 
Father Marquette National Memorial, Michigan 
Gloria Dei (Old Swedes') Church National Historic Site, Pennsylvania 
Green Springs National Historic Landmark District, Virginia 
Historic Camden Revolutionary War Site, South Carolina 
Ice Age National Scientific Reserve, Wisconsin 
International Peace Garden, North Dakota and Canada 
Inupiat Heritage Center, Alaska 
Jamestown National Historic Site, Virginia 
Kate Mullany National Historic Site, New York 
Kettle Creek Battlefield, Georgia 
Lower East Side Tenement National Historic Site, New York 
Natural Bridge State Park, Virginia 
Oklahoma City National Memorial, Oklahoma 
Parkers Crossroads Battlefield, Tennessee 
Pinelands National Reserve, New Jersey 
Red Hill Patrick Henry National Memorial, Virginia 
Roosevelt Campobello International Park, Canada 
Thomas Cole National Historic Site, New York 
Touro Synagogue National Historic Site, Rhode Island 
Wing Luke Museum of the Asian Pacific American Experience, Washington
Adams Memorial, District of Columbia 
Blackwell School National Historic Site, Texas 
Coltsville National Historical Park, Connecticut 
Desert Storm/Desert Shield Memorial, District of Columbia 
Global War on Terrorism Memorial, District of Columbia 
Ronald Reagan Boyhood Home National Historic Site, Illinois
Grand Canyon-Parashant National Monument (Bureau of Land Management unit co-managed with National Park Service)
Charleston National Commemorative Site, Arkansas 
Kennedy-King National Commemorative Site, Indiana 
Quindaro Townsite, Kansas
Abraham Lincoln National Heritage Area, Illinois 
America's Agricultural Heritage Partnership (Silos & Smokestacks National Heritage Area), Iowa 
Appalachian Forest National Heritage Area, Maryland and West Virginia 
Arabia Mountain National Heritage Area, Georgia 
Atchafalaya National Heritage Area, Louisiana 
Augusta Canal National Heritage Area, Georgia 
Baltimore National Heritage Area, Maryland 
Blue Ridge National Heritage Area, North Carolina 
Cache La Poudre River National Heritage Area, Colorado 
Cane River National Heritage Area, Louisiana 
Champlain Valley National Heritage Partnership, New York and Vermont 
Crossroads of the American Revolution National Heritage Area, New Jersey 
Delaware and Lehigh National Heritage Corridor, Pennsylvania 
Erie Canalway National Heritage Corridor, New York 
Essex National Heritage Area, Massachusetts 
Freedom's Frontier National Heritage Area, Kansas and Missouri 
Freedom's Way National Heritage Area, Massachusetts and New Hampshire 
Great Basin National Heritage Route, Nevada and Utah 
Gullah/Geechee Cultural Heritage Corridor, Florida, Georgia, North Carolina, and South Carolina 
Illinois & Michigan Canal National Heritage Corridor, Illinois 
John H. Chafee Blackstone River Valley National Heritage Corridor, Massachusetts and Rhode Island 
Journey Through Hallowed Ground National Heritage Area, Maryland, Pennsylvania, and Virginia 
Kenai Mountains-Turnagain Arm National Heritage Area, Alaska 
Lackawanna Valley National Heritage Area, Pennsylvania 
Maritime Washington National Heritage Area, Washington 
Maurice D. Hinchey Hudson River National Heritage Area, New York 
Mississippi Delta National Heritage Area, Arkansas, Louisiana, and Mississippi 
Mississippi Gulf Coast National Heritage Area, Mississippi 
Mississippi Hills National Heritage Area, Mississippi 
Mormon Pioneer National Heritage Area, Utah 
MotorCities National Heritage Area, Michigan 
Mountains to Sound Greenway National Heritage Area, Washington 
Muscle Shoals National Heritage Area, Alabama 
National Aviation National Heritage Area, Ohio 
National Coal National Heritage Area, West Virginia 
Niagara Falls National Heritage Area, New York 
Northern Plains National Heritage Area, North Dakota 
Northern Rio Grande National Heritage Area, New Mexico 
Ohio and Erie National Heritage Canalway, Ohio 
Oil Region National Heritage Area, Pennsylvania 
Rivers of Steel National Heritage Area, Pennsylvania 
Sacramento-San Joaquin Delta National Heritage Area, California 
Sangre de Cristo National Heritage Area, Colorado 
Santa Cruz Valley National Heritage Area, Arizona 
Schuylkill River Valley National Heritage Area, Pennsylvania 
Shenandoah Valley Battlefields National Historic District, Virginia 
South Carolina National Heritage Corridor, South Carolina 
South Park National Heritage Area, Colorado 
Southwestern Pennsylvania Industrial Heritage Route (Paths of Progress National Heritage Route), Pennsylvania 
Susquehanna National Heritage Area, Pennsylvania 
Tennessee Civil War National Heritage Area, Tennessee 
The Last Green Valley National Heritage Corridor, Connecticut and Massachusetts 
Upper Housantonic Valley National Heritage Area, Connecticut and Massachusetts 
Wheeling National Heritage Area, West Virginia 
Yuma Crossing National Heritage Area, Arizona
Ala Kahakai National Historic Trail, Hawaii 
Appalachian National Scenic Trail, Maine to Georgia 
Arizona National Scenic Trail, Arizona 
Butterfield Overland National Historic Trail, Arkansas to California (7 states) 
California National Historic Trail, Missouri to Oregon 
Captain John Smith Chesapeake National Historic Trail, New York to Virginia 
Chilkoot National Historic Trail, Alaska 
Continental Divide National Scenic Trail, Montana to New Mexico 
El Camino Real de los Tejas National Historic Trail, Louisiana to Texas 
El Camino de Tierra Adentro National Historic Trail, New Mexico to Texas 
Florida National Scenic Trail, Florida 
Ice Age National Scenic Trail, Wisconsin 
Iditarod National Historic Trail, Alaska 
Juan Bautista de Anza National Historic Trail, California 
Lewis and Clark National Historic Trail, Pennsylvania to Washington (16 states) 
Mormon Pioneer National Historic Trail, Illinois to Utah 
Natchez Trace National Scenic Trail, Mississippi to Tennessee 
New England National Scenic Trail, Massachusetts to Connecticut 
Nez Perce (Nee-Me-Poo) National Historic Trail, Montana to Oregon 
North Country National Scenic Trail, Vermont to North Dakota (8 states) 
Old Spanish National Historic Trail, California to New Mexico 
Oregon National Historic Trail, Missouri to Oregon 
Overmountain Victory National Historic Trail, South Carolina to Virginia 
Pacific Crest National Scenic Trail, Washington to California 
Pacific Northwest National Scenic Trail, Montana to Washington 
Pony Express National Historic Trail, Missouri to California 
Potomac Heritage National Scenic Trail, Virginia to Pennsylvania 
Santa Fe National Historic Trail, Missouri to New Mexico 
Selma to Montgomery National Historic Trail, Alabama 
Star-Spangled Banner National Historic Trail, District of Columbia, Maryland, and Virginia 
Trail of Tears National Historic Trail, Georgia to Oklahoma 
Washington-Rochambeau Revolutionary Route National Historic Trail, Massachusetts to Virginia
Alagnak Wild River, Alaska 
Alatna Wild River, Alaska 
Aniakchak Wild River, Alaska 
Bluestone National Scenic River, West Virginia 
Cache la Poudre Wild and Scenic River, Colorado 
Charley Wild River, Alaska 
Chilikadrotna Wild River, Alaska 
Eightmile National Wild and Scenic River, Connecticut 
Farmington National Wild and Scenic River, Connecticut 
Flathead River, Montana 
Great Egg Harbor Scenic and Recreational River, New Jersey 
Housatonic Wild and Scenic River, Connecticut 
John Wild River, Alaska 
Kern River, California 
Kings River, California 
Kobuk Wild River, Alaska 
Lamprey Wild and Scenic River, New Hampshire 
Lower Delaware Wild and Scenic River, New Jersey to Pennsylvania 
Lower Farmington and Salmon Brook Wild and Scenic Rivers, Connecticut 
Maurice Scenic and Recreational River, New Jersey 
Merced River, California 
Middle Delaware River, New Jersey to Pennsylvania 
Missisquoi and Trout National Wild and Scenic River, Vermont 
Missouri National Recreational River, South Dakota to Nebraska 
Mulchatna Wild River, Alaska 
Musconetcong National Wild and Scenic River, New Jersey 
Nashua, Squannacook, and Nissitissit Wild and Scenic Rivers, Massachusetts and New Hampshire 
Niobrara National Scenic River, Nebraska 
Noatak Wild River, Alaska 
North Fork of the Koyukuk Wild River, Alaska 
Obed Wild and Scenic River, Tennessee 
Rio Grande Wild and Scenic River, Texas 
River Styx Wild and Scenic River, Oregon 
Saint Croix National Scenic Riverway, Wisconsin to Minnesota 
Salmon Wild River, Alaska 
Snake River Headwaters Wild and Scenic River, Wyoming 
Sudbury, Assabet and Concord National Wild and Scenic River, Massachusetts 
Surprise Canyon Creek Wild and Scenic River, California 
Taunton Wild and Scenic River, Massachusetts 
Tinayguk Wild River, Alaska 
Tlikakila Wild River, Alaska 
Toulumne River, California 
Upper Delaware Scenic and Recreational River, New York to Pennsylvania 
Virgin Wild and Scenic River, Utah 
Wekiva Wild and Scenic River, Florida 
Westfield Wild and Scenic River, Massachusetts 
White Clay Creek Wild and Scenic River, Pennsylvania 
Wolf River, Wisconsin 
Wood-Pawcatuck Watershed Wild and Scenic Rivers, Connecticut and Rhode Island 
York Wild and Scenic River, Maine