National Wildlife Refuge System (NWRS) is a system of protected areas of the United States managed by the United States Fish and Wildlife Service (FWS), an agency within the Department of the Interior. The National Wildlife Refuge System is the system of public lands and waters set aside to conserve America's fish, wildlife, and plants. Since President Theodore Roosevelt designated Florida's Pelican Island National Wildlife Refuge as the first wildlife refuge in 1903, the system has grown to over 568 national wildlife refuges and 38 wetland management districts encompassing about 856,000,000 acres (3,464,109 km2).

The protected areas of the United States are managed by an array of different federal, state, tribal and local level authorities and receive widely varying levels of protection. Some areas are managed as wilderness, while others are operated with acceptable commercial exploitation. As of 2022, the 42,826 protected areas covered 1,235,486 km2 (477,024 sq mi), or 13 percent of the land area of the United States. This is also one-tenth of the protected land area of the world. The U.S. also had a total of 871 National Marine Protected Areas, covering an additional 1,240,000 sq mi (3,200,000 km2), or 26 percent of the total marine area of the United States.