The first part of what was known in New Jersey as "The Great Swamp" that had been assembled in 1959 and was donated for perpetual preservation by the park service of the federal government in 1960, was declared a National Natural Landmark in May 1966.

The Great Swamp is the remnant of the bottom of the once-mighty Glacial Lake Passaic that approximately 15,000 to 11,000 years ago stretched across 30 by 10 miles (48 by 16 km) in what is presently northern New Jersey.

When the plug collapsed, the river still was forced to travel north through the range before finding a new outlet near present-day Paterson where it could manage the eastern turn toward the sea.

Some ten thousand years ago, Amerindians arrived in the area and established settlements shortly after the retreat of the glacier, hunting, fishing, and farming.

Their efforts to prevent the development of an airport in the swamp became public knowledge on December 3, 1959, when four of its members (Kafi Benz, Joan Kelly, Esty Weiss, and Betty White) were expelled from a meeting at the Essex House in Newark that had been organized to generate support for its construction.

[5] Between the two organizations and, in less than a year, enough property in the core of the swamp was quickly purchased, assembled, and donated to the federal government to qualify for perpetual protection as a national wildlife refuge.

The major routes of birds migrating along the eastern portion of the United States follow the corridor that includes the Great Swamp as an important stopping place for rest and nutrition.

Deer, fish, fox, frogs, muskrat, raccoons, snakes, turtles, as well as many insects and a wide variety of wildflowers and plants call the refuge home.

[12] Within the Great Swamp there also is a nonprofit bird-rehabilitation center founded in 1977, called The Raptor Trust, mainly specializing in birds of prey, such as eagles, hawks, and owls.