It is one of a chain of volcanic seamounts extending from Hawaii up to the tip of the Aleutian Islands, known as the Hawaii-Emperor chain. It was formed roughly 28 million years ago when the seabed underneath it was over the same hot spot from which Hawaiian Islands have been erupted.
The atoll, which has no indigenous inhabitants, is an unincorporated territory of the United States formerly administered from Washington, DC, by the US Navy's Naval Facilities Engineering Command, Pacific Division and defense is the responsibility of the US; however, this facility has been operationally closed since September 10, 1993. On October 31, 1996, through a presidential executive order, the jurisdiction and control of the atoll was transferred to the US Fish and Wildlife Service of the US Department of the Interior as part of the National Wildlife Refuge[?] system. Its data code is MQ. It is open to the public for wildlife-related recreation in the form of wildlife observation and photography, sport fishing, snorkeling, and scuba diving. The economy is based on providing support services for these activities. All food and manufactured goods must be imported.
The atoll has some 32 kilometers of roads, 7.8 kilometers of pipelines, one port (on Sand Island), and three airstrips (two paved, around 2000 meters long, and one unpaved, around 1000 meters long).