The United States holds twenty-seven World Heritage properties: thirteen cultural, thirteen natural and one mixed
Background
The World Heritage Centre's State Party page for the United States of America lists 27 properties inscribed on the World Heritage List.
They are grouped as Cultural 13, Natural 13 and Mixed 1.
The one mixed property, meeting both cultural and natural criteria, is Papahānaumokuākea.
Cultural properties include Independence Hall, the Statue of Liberty, Mesa Verde National Park, Cahokia Mounds State Historic Site, Chaco Culture, Taos Pueblo, San Antonio Missions, Monumental Earthworks of Poverty Point and Hopewell Ceremonial Earthworks.
Natural properties include Yellowstone National Park, Grand Canyon National Park, Everglades National Park, Great Smoky Mountains National Park, Yosemite National Park, Olympic National Park, Mammoth Cave National Park, Carlsbad Caverns National Park, Redwood National and State Parks, Hawaii Volcanoes National Park and Okefenokee National Wildlife Refuge.
The same page records the state party's ratification of the World Heritage Convention, 4 Mandates to the World Heritage Committee and 73 State of Conservation Reports.
The United Nations member-states list gives the United States of America a Date of Admission in the form 24-10-1945, the same date as a group of other founding members.
In plain words
Mixed property Mixed World Heritage property — A World Heritage property inscribed for both cultural and natural outstanding universal value rather than one of the two alone.
Tentative List Tentative List — A state party's own inventory of the properties it intends to consider for nomination to the World Heritage List later.