Home to over 5,000 archaeological sites, including cliff dwellings of the Ancestral Pueblo peoples of southwestern Colorado, Mesa Verde was designated a national park in 1906. In 1978, it earned a spot among an elite group of only 12 places around the world named the first UNESCO World Heritage Sites. Mesa Verde was one of two sites in the U.S. — the other was another national park, Yellowstone.

The namesake thermal waters of Hot Springs National Park in Arkansas were long used by Indigenous peoples for their healing benefits. President Andrew Jackson declared the region a preservation and recreation area in 1832 — one of the first of its kind in the U.S. and a full 40 years before Yellowstone National Park became the country’s first national park. The area officially became a national park in 1921.

Delaware may have been the first state, but it didn’t have a national park site for nearly a century after the National Park Service was established. In 2013, President Obama recognized the First State National Monument — to the great relief of conservationists who had lobbied for a park for decades. The site comprises historic buildings like the Old New Castle Courthouse and Dover Green.

Though the iconic 630-foot-tall and 630-foot-wide Gateway Arch wasn’t completed until 1963, the area around the monument had been designated the Jefferson National Expansion Memorial since 1935. In 2018, Congress voted to reclassify the site as Gateway Arch National Park. It is the smallest of the country’s 63 national parks, covering just over 90 acres.

In 1872, Yellowstone became America’s first national park, and three years after Yellowstone, Congress established Mackinac National Park on Michigan’s Mackinac Island. But by the 1890s, the U.S. Army proposed abandoning the park, so Michigan’s governor petitioned for the land to be transferred to the state, and it became Michigan’s first state park in 1895.

The smallest unit of the National Park System is the Thaddeus Kosciuszko National Memorial, which covers just 0.02 acres in downtown Philadelphia. It is the boarding house where Thaddeus Kosciuszko lived from 1797 to 1798. Kosciuszko was a military engineer who designed fortifications and blockades during the American Revolution.

In 2016, President Barack Obama announced the establishment of the Katahdin Woods and Waters National Monument in Maine to honor the 100th anniversary of the National Park Service. The 90,000-acre park is adjacent to Baxter State Park, which is the northern terminus of the Appalachian Trail.

In 1980, Jimmy Carter signed the Alaska National Interest Lands Conservation Act (ANILCA) to conserve large parts of Alaska. The bill created 10 national parks and preserves, two national monuments, nine wildlife refuges, and 25 wild and scenic rivers.

The 26th President’s namesake park is located in the North Dakota badlands, and got its name because Theodore Roosevelt had a residence there. When Roosevelt served as President from 1901 to 1909, he established more than 200 national parks, forests, wildlife reserves, and monuments across 230 million acres of public land, earning him the nickname of the “conservationist President.”

The first national historic site in the U.S. was established in 1938 in Salem, Massachusetts. Located along the city’s waterfront, the Salem Maritime National Historic Site covers nine acres and 12 historic buildings that preserve more than six centuries of maritime history in New England.

Flowing 135 miles from the Boston Mountains to the Ozarks, the Buffalo National River in northern Arkansas became the first national river in the United States in 1972. The national river designation prevents its use for industrial purposes, and it remains one of the few undammed rivers in the lower 48.

Since the foundation of the National Park Service in 1916, the United States has designated three protected national lakeshores. Apostle Islands National Lakeshore is located in Wisconsin, while the other two — Pictured Rocks National Lakeshore and Sleeping Bear Dunes National Lakeshore — are in Michigan.

Shortly after his graduation from the University of Michigan in 1936, Gerald Ford worked as a seasonal park ranger at Yellowstone National Park. Among his duties, Ford worked at the bear-feeding truck, a dangerous practice that has been discontinued. Ford returned to Yellowstone during his presidency in 1976 and delivered a speech at Old Faithful, describing his park ranger experience as “one of the greatest summers of my life.”

The Civilian Conservation Corps (CCC) was established in 1933 as part of President Franklin Roosevelt’s New Deal program. The CCC created jobs for men ages 18 to 25, working on improvements to public lands, forests, and parks. An estimated 3 million men participated in the program, which lasted nine years (until the start of World War II) and helped shape the modern national park system.

The National Trails System Act was established in 1968. The first two national scenic trails were the Appalachian Trail in the East and the Pacific Crest Trail in the West. Since 1968, 30 long-distance trails have been created as part of the National Trails System. The longest is the American Discovery Trail, traversing 6,800 miles from California to Delaware.

Maine’s Acadia National Park was the first national park established east of the Mississippi River in 1916. And it’s been a hit ever since: Today, Acadia is the second-most-visited national park east of the Mississippi, after Great Smoky Mountains National Park.

In 1916, the National Park Service Organic Act created an agency to manage the National Park System. The NPS is part of the Department of the Interior and has a dual mission of conserving park resources and providing public access. Each national park has its own goals and directives, though, such as recreation or environmental conservation or historical preservation.

President Theodore Roosevelt declared Devils Tower in Wyoming as the country's first national monument in 1908. The striking 867-foot-tall natural formation rising from the prairie of the Black Hills in Wyoming has long been a sacred site for the Indigenous peoples of the area.

The Antiquities Act of 1906 established the country’s first national historic preservation policy. Before this law, specific areas (like Yellowstone) were set aside after an act of Congress and approval from the President. But the Antiquities Act streamlined the process, making it a simple administrative action.

An expedition led by Ferdinand Hayden in 1871 laid the foundation for America's fascination with Yellowstone. In 1872, Congress approved a proposal to set aside 1.2 million acres of public land, which stretched across the future states of Wyoming, Montana, and Idaho. President Grant soon signed the Yellowstone Act into law, thus establishing America's first national park.