Three Hawaiian parks -- Haleakala National Park, Hawai'i Volcanoes National Park, and Kalaupapa National Historical Park -- combined have 244 endangered and threatened species – more than any other parks in the country. This is not surprising, considering Hawaii has more listed species than any state in the country.

Haleakalā National Park on the island of Maui, Hawaii, holds the somber title of having the highest concentration of endangered species in the U.S. National Park System. Due to Hawaii's extreme geographic isolation, the park evolved a high degree of "endemism," meaning many of its plants and animals are found nowhere else on Earth. However, this isolation also makes the ecosystem incredibly fragile and susceptible to invasive species. The park is a critical sanctuary for the Haleakalā Silversword (a plant that can live for 90 years and blooms only once) and several species of Hawaiian Honeycreepers, which are facing extinction due to avian malaria carried by invasive mosquitoes. In 2026, the National Park Service is engaged in intensive "biocompatibility" projects to save these birds. Other parks with high numbers include Everglades National Park in Florida and Great Smoky Mountains National Park, but in terms of the "percentage" of its native flora and fauna currently listed as threatened or endangered, Haleakalā remains the most critical "front line" for biodiversity conservation in America.