This year is the 100th anniversary of the National Park Service. To celebrate, the U.S. Postal Service is issuing 16 new stamps that showcase the beauty, history and culture of America's national park sites. The Postal Service is releasing the stamps individually over a three-week period with the big debut for the new series to be held on June 2 as part of World Stamp Show-NY 2016.

To date, the Postal Service has previewed 11 of the 16 National Park Forever Stamps. Many of the stamps highlight the natural beauty of the nation's parks, such as the contrasting textures and landforms of Arches National Park in Utah, the wild horses of Assateague Island National Seashore in Maryland, and a delicate water lily in bloom at Washington, D.C.'s Kenilworth Park & Aquatic Gardens.

But like the National Park Service itself, not all of the stamps are focused on nature. Some highlight historic sites, such as Maine's Bar Harbor Head Light — the iconic lighthouse featured on the Acadia National Park stamp — or the administration building featured on the Bandelier National Monument stamp. Incidentally, Bandelier National Monument, a New Mexico site dedicated to preserving the homes, petroglyphs and territory of the Ancestral Puebloans is also celebrating its centennial anniversary this year.

Other park sites featured on the National Park Forever stamps include Carlsbad Caverns National Park in New Mexico, Florida's Everglades National Park, Glacier Bay National Park and Preserve in Alaska, Arizona's Grand Canyon National Park, Gulf Islands National Seashore in Florida and Mississippi, and Haleakalā National Park on the island of Maui in Hawaii.

Take a look at the series so far. And follow @USPSStamps on Twitter to get a glimpse of rest of the stamps as they are released.