Dedication of the Everglades National Park was marked by a 3-cent green stamp issued on December 5, 1947. The design features a great white heron superimposed upon an outline map of Florida that shows the Everglades area. The only sub-tropical preserve in North America, Everglades National Park boasts a unique mix of wildlife. Many bird species are found there, and it is the only place in the world co-habited by alligators and crocodiles. The park is now endangered as a result of ill-conceived man-made water distribution devices. Some of these have recently been undone, allowing a reversion to more natural water flow.