The United States began establishing wildlife refuges under Theodore Roosevelt. In 1903 he declared Pelican Island in Florida a refuge for the brown pelican, protecting a species that was close to extinction. In 1906 Congress closed all refuges to hunting, and in 1908, it established the National Bison Range refuge in Montana to protect that endangered species.

The refuge system continued to expand later in the century, with a primary emphasis on migratory waterfowl. In 1929 Congress passed the Migratory Bird Convention Act, followed by the Migratory Bird Hunting Stamp Act of 1934, which provided funding for waterfowl reserves. Wetlands now make up roughly 75 percent of the national wildlife refuges and serve as linked management units along the major waterfowl flyways.

The second focus in the expansion of the refuge system has been the need to protect endangered and rare species. Several acts have been passed for this purpose...