Celebrate 100 years of National Parks this weekend

They’re having a birthday-- and it's a big one. The National Park Service turns 100 on Aug. 25 and parks around the country are celebrating the milestone.

Starting Thursday, entrance to the 124 parks that usually charge admission is free through Sunday (Aug. 28). Throughout the nation, special events at over 400 parks will celebrate the centennial.

From birthday cakes and cupcakes to special classes and programs, most parks have something special planned. 

National parks may be synonymous with camping and hiking today but Americans haven't always been able to enjoy these protected lands.

The story of the national parks started in 1872 with the creation of the first park, Yellowstone National Park, with the Yellowstone Act. The land was saved from private development when President Ulysses S. Grant signed the Yellowstone National Park Protection Act into law, March 1, 1872.

Thanks, in part, to the stunning nature photography of William Henry Jackson, official photographer of the United States Geological and Geographical Survey of the Western Territories, 2.2 million acres became the world’s first national park. Known for its geysers, hot springs and bison herd, Yellowstone was the beginning of what was to become the National Park Service in 1916.

On Aug. 25, 1916, President Woodrow Wilson signed into law an act creating the National Park Service. In the years since, it's expanded to include over 400 different parks and park monuments throughout the U.S.

More than 300 million visited National Park Service sites and parks in 2015, according to NPS. Among the parks, Great Smoky Mountains National Park was the most visited at 10.7 million recreational visits. Grand Canyon National Park received 5.5 million visitors followed by Rocky Mountain National Park with 4.155 million visitors.

Spurred in large part by heavy promotion during the centenniel, visits to the parks are up 3.36 percent compared to last year.

Haven't visited a park yet? Here are eight fun ways to celebrate:

--Be Part of the Human Arrowhead Emblem. Join the 1,000-plus visitors who will meet on the National Mall and Memorial Parks in Washington on Thursday, Aug. 25, to create a living version of this well-known emblem for the National Park Service. NPS employees, volunteers and partners will use brown, green and white umbrellas to create the symbol beginning at 10 AM. Those gathering are asked to pre-register and assemble on the west side of the Washington Monument at 9 a.m. The first 1,000 participants will receive a commemorative T-shirt. They’ll also be able to keep their umbrellas-- rain or shine.

--Follow the Footsteps of Alaska Conservationists.  Denali National Park and Preserve historian Erik Johnson, also an Alaska Geographic educator,  leads the way, Aug. 24 through 26, using the notes of Charles Sheldon to find the mountain ridges where he first discovered Dall sheep. The course also tracks the path of biologist Joseph Dixon’s journey through the park. Cost is $315 for Alaska Geographic members; $350 for non-members.

--Meet the new Theodore Roosevelt National Park Quarter. The United States Mint and National Park Service officials will launch the new coin at Painted Canyon Visitor Center in North Dakota on Thursday. Parking will be limited but a free shuttle service is being offered from Medora Musical Hill and from the park's Cottonwood Campground. Return trips are scheduled following the ceremony.

--Eat Cupcakes with the Rangers. Friends of the Theodore Roosevelt National Park will provide Birthday Cupcakes with the Rangers in the Juniper Picnic Area in the North Unit at 7:30 p.m CT at the Theodore Roosevelt National Park.

--Go Back in Time. Learn about Gen. Ulysses S. Grant at the Gen. Grant National Memorial in New York City. A West Point graduate, he served two terms as President of the United States. Hear a Grant impressionist relay his life's work on Aug. 25.

--Say Aloha. Hawaii Volcanoes National Park celebrates the NPS Centennial with the Na Leo Manu Hawaiian Concert Series Friday, Aug. 26 from 6 p.m. to 9 p.m. at Kīlauea Military Camp's Kīlauea Theater. The program will feature authentic Hawaiian music and a hula troupe.

--Learn about Biodiversity in Lava Flows.  Join in a “mini” BioBlitz to observe and document the biodiversity that thrives in the lava flows and native rainforests of the Kilauea and Mauna Loa Volcanoes Saturday, Aug. 27, at Hawaii Volcanoes National Park, Pa Hula near the near Kīlauea Visitor Center on the Big Island of Hawaii. Field inventories begin at 7 a.m. and continue until the early afternoon.

--Have Birthday Cake. The Florida National Parks Association is hosting a National Parks Birthday Party Thursday at the Coral Gables Museum in Coral Gables from 6:30 p.m. to 8:30 p.m. The event highlights “This Land is Your Land: A Second Century for America’s National Parks,” an exhibit of images, videos and artifacts from the collections of Biscayne, Dry Tortugas and Everglades National Parks and Big Cypress National Preserve.