In celebration of its 100th anniversary, the National Park Service announced 10 days where you can attend any of the 400 national parks for free. But what many people don't know is that you can already enter hundreds of national parks without paying entrance fees. Here's a look at parks you can enter for free.
Alabama: Horseshoe Bend National Military Park
The state of Alabama had its bloody beginnings at Horseshoe Bend National Military Park. An 1814 battle was waged at Horseshoe Bend, leading to a treaty that required the native population to cede 23 million acres of land to the U.S. From this territory, the state of Alabama was carved.
At this national park, you'll find breathtaking sights home to 901 plant species and 354 species of wildlife. Cycle along the Tour Road that visits the solemn battleground or paddle a canoe on the winding Tallapoosa River.
Alaska: Gates of the Arctic National Park
National parks don't get any more wild than this one. Gates of the Arctic National Park is a can't-miss Alaskan destination. Rivers wind through the park, making it an ideal away-from-it-all destination for packrafting, backpacking or kayaking. Note that this park does not have roads or established trails.
Arizona: Montezuma Well National Monument
Visit the spot where life began, according to Yavapai legend, at Montezuma Well National Monument. Although access to the nearby Montezuma Castle National Monument costs $10, the Montezuma Well is free to access. There, you'll see Native American ruins alongside the well and follow a nature trail as it winds below trees beside Beaver Creek.
Arkansas: Hot Springs National Park
Hearken back to the Golden Age of Bathing on your visit to Hot Springs National Park. Go ahead and drink the water — or "quaff the elixir" as they used to say back in the day. It's safe, healthy for you and free at fountains and water bottle fill sites around the park.
Meander through eight bathhouses built between 1892 and 1923. Some bathhouses are now home to National Park Service offices, shops and museums. Others still provide baths in the thermal pools, but you'll pay a fee to use them.
California: Channel Islands National Park
Experience California the way it used to be at Channel Islands National Park. The chain of islands is one of the best free national parks for an away-from-it-all experience. Bring your snorkel and fins to explore kelp forests, sea caves and coves of colorful fish. Or, explore island trails and relax on a remote beach, a little patch of paradise you'll likely have all to yourself. Note that you might need to pay for a boat or plane ride to the islands.
Colorado: Hovenweep National Monument
Discover six prehistoric villages that once housed more than 2,500 people between 500 and 1300 A.D. See multistory towers clinging to the edge of rocky cliffs. The park is a designated International Dark Sky Park, making it one of the best places to go stargazing.
Connecticut: Weir Farm National Historic Site
You won't have to imagine you've stepped into an Impressionist landscape at Weir Farm — you'll be in one. The historic site is the only national park devoted to American painting.
Explore a picturesque farmhouse, stone walls and gardens for free at the park. Feeling inspired? Pick up free art supplies at the park to experience a memorable family vacation.
Delaware: First State National Historic Park
The U.S. has come a long way when it comes to religious and ethnic tolerance. But Delaware was actually one of the first regions to embrace diversity, even before it became a state in 1787.
Recount the lives of Swedish and Finnish settlers from as early as 1699 as you read ancient tombstones at the Old Swedes Church in Wilmington. Or visit the two-story brick home of John Dickinson, aka the "penman of the Revolution," who inspired the country to independence.
Florida: Biscayne National Park
You'll find so much more at Biscayne National Park than on the miles of sandy beaches that Miami is famous for. Grab your snorkel and discover underwater shipwrecks along the Maritime Heritage Trail, or keep your feet dry to walk in the footsteps of pineapple farmers. Visit during summer to witness loggerhead sea turtles nesting in the sand, or escape to this national park for the perfect vacation destination to escape the cold.
Georgia: Jimmy Carter National Historic Site
Learn what life was like growing up for the 39th president of the United States at the Jimmy Carter National Historic Site. Visit his boyhood farm where wayside audio exhibits let you hear about Carter's childhood in his own voice. Recapture the excitement of his 1976 run for presidency at a free museum at the Plains Train Depot. Browse through exhibits at the Plains High School and several visitors centers.
Hawaii: World War II Valor in the Pacific National Monument
Take a break from salty beaches and swaying palms to revisit a pivotal time in American history at the World War II Valor in the Pacific National Monument. See the sunken battleship USS Arizona still at rest where she was struck down about 15 minutes into the Japanese attack on Pearl Harbor. Arrive early to get one of 1,300 free tickets to see the USS Arizona Memorial.
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Idaho: Nez Perce National Historic Park
Marvel at the mountains and valleys at Nez Perce National Historic Park. The area was home to the Nez Perce. Put on your hiking boots and walk in the footsteps of Lewis and Clark at Canoe Camp.
Illinois: Pullman National Monument
Pullman wasn't your usual factory town. The Queen-Anne-style architecture and aesthetic appeal seem idyllic, but Pullman has its own bloody tales to tell. Discontented workers and U.S. Army troops clashed in 1894, leaving dozens dead. Today, you can revisit the neighborhood's storied history as you walk through the green spaces of Arcade Park or marvel at the architecture of this historic park.
Indiana: George Rogers Clark National Historical Park
Watch colorful kites dip and soar along the Wabash River at the George Rogers Clark National Historical Park. And don't miss the elaborate memorial dedicated to the famed American frontiersman Colonel George Rogers Clark. Relive his travels as you gaze at seven 28-foot murals.
Iowa: Effigy Mounds National Monument
Visit more than 200 American Indian mounds at Effigy Mounds National Monument. Discover mounds in the shapes of turtles, bison, bears, deer and other animals as well as conical burial mounds in the park. Watch a 15-minute film on mound building at the visitors center and strike out on trails through the area's breathtaking terrain. And, while you're in Iowa, don't miss its unique roadside attraction: the largest frying pan in the world.
Kansas: Fort Larned National Historic Site
Immerse yourself in authentic frontier military life at Fort Larned National Historic Site. Stroll through historic buildings restored to their original appearance and wander nature trails. During special events, dive deeper into this historical site as you interact with staff dressed in period clothing.
Kentucky: Mammoth Cave National Park
Looking for a good place for a free family vacation? As the longest known cave system in the world, Mammoth Cave National Park is among one of the coolest places in the U.S. to visit with kids. You won't get through all 400 miles of the cave, but you'll have a great time exploring what one of its early guides called a "grand, gloomy and peculiar place."
Louisiana: Jean Lafitte National Historical Park
Explore not just one but six sites spread over southern Louisiana at Jean Lafitte National Historical Park. See the French Quarter in a new way as you learn about its unique history. Browse historic homes and museums. Then, watch alligators basking on the banks of a bayou at Barataria Preserve or clap along to Cajun music at the Wetlands Acadian Cultural Center.
Maine: Roosevelt Campobello International Park
Visit President Franklin Roosevelt's beloved summer getaway at Roosevelt Campobello International Park. Wiggle your toes in the sand or explore the island trails to discover forests, bogs and beaches. The U.S. and Canada jointly administer, staff and fund the park. Though technically in Canada, the U.S. National Park Service lists it as in Lubec, Maine.
Maryland: Glen Echo Park
You might not initially think of amusement parks when you think about visiting a national park. But in the early 1900s, Glen Echo Park was Maryland's answer to Atlantic City and Coney Island. Today's Glen Echo Park hearkens back to the old days with its historic buildings and attractions, a perfect backdrop for throwback vacation photos.
Massachusetts: Saugus Iron Works National Historic Site
You don't have to wait for national park free days to learn how iron and steel is made. Visit Saugus Iron Works National Historic Site to see free demonstrations of the process that made this the birthplace of the American iron and steel industry. Enjoy the natural beauty surrounding the ironworks by hiking its nature trail or strolling through its 17th century herb garden.
Michigan: River Raisin National Battlefield Park
After the U.S. defeat at River Raisin, "Remember the Raisin" was the battle cry for the remainder of the War of 1812. You'll remember this park for its picturesque riverfront. Hike a 0.6-mile loop through the battlefield, and browse through artifacts and exhibits in the visitors center.
Minnesota: Voyageurs National Park
Let your cares slip away as you immerse yourself in the sounds, scents and sights of a boreal forest at Voyageurs National Park. Paddle interconnected water routes in your canoe or kayak, or have a picnic at the water's edge. At night, gaze up at the stars. In the winter, go snowshoeing.
Mississippi: Natchez National Historical Park
Explore the grand architecture of antebellum mansions at Natchez National Historical Park. Although there are small entrance fees to enjoy guided tours inside most of the mansions, you won't have to pay a penny to explore the William Johnson House. The famed barber built the home from bricks he gathered from buildings devastated by the tornado of 1840.
Missouri: George Washington Carver National Monument
Frail childhood health gave George Washington Carver enough freedom from plantation chores so he could tend to a secret garden hidden in the Missouri woodland. Take a journey along the 1-mile Carver Trail to discover the woodland that inspired Carver as a child. Learn about his life at the visitors center museum, visit the graves of the plantation owners and see where the famous peanut product inventor was born.
Montana: Grant-Kohrs Ranch National Historic Site
Not only is Montana a great state for low-cost camping spots, it's home to the Grant-Kohrs Ranch National Historic Site. The ranch house was the center of a cattle empire once spanning 10 million acres. It now honors America's cattleman.
Nebraska: Homestead National Monument of America
The Homestead Act of 1862 spurred people of all backgrounds to head to the frontier to claim land. Follow the Quilt Trail to discover the meaning behind popular quilt patterns made by thrifty women readying their families for the journey west. Or visit the Palmer-Epard Cabin and imagine what life was like living in its one room with 10 children.
Nevada: Great Basin National Park
From sage-covered desert foothills to the aspen-shrouded slopes of Wheeler Peak, you'll find a wide range of natural diversity at Great Basin National Park. Even though the park receives less than 10 inches of rainfall annually, you can discover more than 800 species of plants along its trails. Keep your eyes peeled for wildlife, too. You might notice a bighorn sheep peering down from lofty heights or a pygmy rabbit scuttling into the underbrush.
New Hampshire: Appalachian National Scenic Trail
If you've ever thought of hiking along the Appalachian Trail, New Hampshire is one state where you can enjoy the public footpaths. The trail rolls 161 miles through the state, with elevations ranging from 400 feet above sea level to nearly 6,300. Start at AMC's Pinkham Notch Visitor Center for a scenic hike into the White Mountains.
New Jersey: Paterson Great Falls National Historical Park
Paterson Great Falls National Historical Park is more than just another pretty waterfall. It's also the site of the first planned industrial city in the U.S. Locomotives, paper and fabrics were manufactured in the area, with power harnessed from the falls.
New Mexico: El Morro National Monument
Discover an oasis in the desert at El Morro National Monument. The natural watering hole is tucked at the base of colorful sandstone cliffs. Walk the Inscription Trail to read and see the history behind the watering hole. Thousands of petroglyphs and inscriptions bear witness to the visitors who sought refreshment there throughout the centuries.
New York: National Parks of New York Harbor
Home to the most popular tourist attractions in the U.S., it's no wonder New York has some of the best national parks that are free. The National Parks of New York Harbor boast 23 free destinations. Take a tour at the Castle Clinton on Manhattan Island's southern tip, or visit Federal Hall, where George Washington became the first president and the nation's first Congress and Supreme Court worked.
North Carolina: Fort Raleigh National Historic Site
Fort Raleigh National Historic Site is one of the best national parks to unearth the country's earliest history. Learn about Native Americans and the first New World settlers. See a monument commemorating the Roanoke Island Freedman's Colony, stroll through forest trails and more.
North Dakota: Knife River Indian Villages National Historic Site
Soak in the culture of the Hidatsa people at Knife River Indian Villages. Walk the Village Trail to view the remains of villages and experience a reconstructed earth lodge with its garden and drying racks. Pick up a free birding checklist at the visitors center, and see how many you can spot along the park's trails.
Ohio: Cuyahoga Valley National Park
Don't forget your camera when you visit Cuyahoga Valley National Park. It is home to Everett Covered Bridge, one of the top places for photography in the national parks system. Stroll by the Ohio and Erie Canal or hike to Brandywine Falls.
Oklahoma: Chickasaw National Recreation Area
Bait your hook — Chickasaw National Recreation Area is one of the best national parks for fishing in the state of Oklahoma. Lake of the Arbuckles has 36 miles of shoreline with protected coves and clear water. Or head to the smaller Veterans Lake. Its 2.8-mile shoreline has handicapped accessible trails, a fishing dock and plenty of picnic areas.
Oregon: Oregon Caves National Monument
Oregon Caves National Monument is one of the nation's free national parks, but you'll have to stay above ground to keep your trip free. Explore numerous hiking trails in the park and catch panoramic views of the Siskiyou Mountains. Head inside the visitors center to experience interactive exhibits on the caves, mountains and wild inhabitants.
Pennsylvania: Valley Forge National Historical Park
Visit the 1777-78 winter encampment of General Washington's army at Valley Forge National Historical Park. Drive a 10-mile self-guided tour to drink in the park's natural beauty and learn how the men survived the winter. And don't miss Washington's headquarters.
Rhode Island: Blackstone River Valley National Historical Park
This national park is still in its infancy, but there's still plenty to do. Take self-guided walking tours to discover historic mills and marvel at elaborate architecture.
South Carolina: Congaree National Park
Discover 25 miles of hiking trails and a 2.4-mile boardwalk at Congaree National Park. For a change of pace, observe the forest from the vantage of the water by paddling down marked water trails in your canoe or kayak. For a more adrenaline-filled adventure, take one of these trips.
South Dakota: Minuteman Missile National Historic Site
Visit the site of the historical missile silo Delta-09. It housed the Minuteman Missile — a 1.2-megaton nuclear warhead — from the 1960s to the 1990s.
Tennessee: Great Smoky Mountains National Park
Jump in the car and drive some of the park's 384 miles of road. Picnic by a scenic waterfall, see the Place of a Thousand Drips or hike numerous trails during your trip.
Texas: San Antonio Missions National Historical Park
In the early 1700s, missions were the hub of survival, offering protection from Apache attacks and help during times of drought and disease. Visit four missions at this historical park and explore other sights.
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Utah: Timpanogos Cave National Monument
Hike your way to three limestone caves in remote Utah. Although you'll need to pay for a tour to enter the caves, there's plenty to see around the caves that's free. Spy colorful Western Tanagers, Steller's jays, hummingbirds and more. Bring a picnic and stroll a half-mile down to Swinging Bridge for views of the American Fork River. Then, go fishing for rainbow or brown trout.
Vermont: Marsh-Billings-Rockefeller National Park
Put on your hiking boots and bring a camera for inspiring hikes in Marsh-Billings-Rockefeller National Park. Take an easy 1.25-mile nature walk past gardens and a young tree plantation on the Junior Ranger Loop. Or hike the Pogue Loop Trail around the park's 14-acre pond. For a more strenuous hike, ascend Mount Tom or South Peak for panoramic views of the countryside.
Virginia: Wolf Trap National Park for the Performing Arts
Visit the only national park dedicated to the performing arts. Although the summer-only performances cost money, you won't have to pay a dime to hear the songbirds of nature. Hike the Wolf Trap Trail to explore park woodlands and wetlands and discover dozens of species of birds regaling you with their own special song.
West Virginia: Chesapeake & Ohio Canal National Historical Park
Head to Chesapeake & Ohio Canal National Historical Park to uncover natural and historic gems. Entrance to the towpath except from Great Falls is free. Learn about the C&O Canal on the free Williamsport Launch Boat Program and enjoy sights on the open water.
Wisconsin: Apostle Islands National Lakeshore
Walk along dramatic windswept beaches and rugged cliffs at Apostle Islands National Lakeshore. Bring your kayak to explore sea caves along Lake Superior's shoreline. If you want to keep your feet planted, explore 50 miles of trails that will take you through old farm sites and quarries, and along beaches and scenic overlooks.
Wyoming: Fossil Butte National Monument
Pop into the visitors center at Fossil Butte National Monument to discover the fossilized records of fish, reptiles, plants and insects that once called Fossil Lake home. Let your kids create their own fossil souvenir and watch as experts process fossils. Outside, visit aspen-shaded picnic areas or set out on trails to drink in the natural beauty.
Corrections: The summer cottage in Roosevelt Campobello International Park is Franklin Roosevelt's cottage, not Theodore's as originally published. The park is located in New Brunswick, Canada, though its mailing address is in Maine, according to the National Park Service