On this day in 1916, President Woodrow Wilson signed the Organic Act, which established the National Park Service and its fundamental mission, philosophy and policies.

Did you know that there were national parks before the National Park Service existed?

In 1872, the Yellowstone National Park Act was signed into law, establishing the world’s first true national park. According to NPS, this act withdrew more than two million acres of the public domain in the Montana and Wyoming territories from settlement, occupancy or sale to be “dedicated and set apart as a public park or pleasuring-ground for the benefit and enjoyment of the people.”  It placed the park under control of the Secretary of the Interior.

The Department of the Interior was overseeing 14 national parks (including Yellowstone National Park), 21 national monuments and the Hot Springs and Casa Grande Ruin reservations when the Organic Act was signed. Today, the National Park Service system covers more than 84 million acres in every state, the District of Columbia, American Samoa, Guam, Puerto Rico and the Virgin Islands.

Jefferson National Expansion Memorial is celebrating the anniversary all day today. All visitors to the Gateway Arch will enjoy $3 off their adult Journey to the Top tram ride ticket, and free Arch Entry-only tickets. You can purchase yours by calling 877-982-1410 or visiting the Arch Ticketing and Visitor Center at the Old Courthouse. (Regardless of type, a ticket is required to enter the Gateway Arch facility.)

All day in the Gateway Arch lobby, visitors will enjoy free interactive ranger programs, as well as try on NPS uniforms and pose for photos. Kids ages 5 through 12 are invited to participate in the Junior Ranger program. Upon completion of the program’s activity booklet, they’ll earn a Junior Ranger badge.

Starting today, the 365-day countdown begins to the National Park Service’s Centennial. Visit www.findyourpark.com to discover how you can find, share and support your parks during this year-long celebration.

Happy birthday, NPS!