[7] Thurston formally claimed Kingman for the United States by reading the following declaration while standing on its shore: Be it known to all people: That on the tenth of May, A.D. 1922, the undersigned agent of the Island of Palmyra Copra Co., Ltd., landed from the motorship Palmyra doth, on this tenth day of May, A.D. 1922, take formal possession of this island, called Kingman Reef, situated in longitude 162 degrees 18' west and 6 degrees 23' north, on behalf of the United States of America and claim the same for said company.

A copy of the declaration, along with a U.S. flag and clippings from The Honolulu Advertiser newspaper, were left on Kingman to document the claim.

It had been decided that the Kingman Reef lagoon, located 1,600 miles (2,600 km) north of Samoa, would be suitable for overnight stops for planes en route from the U.S. to New Zealand.

A supply ship, the North Wind, was stationed at Kingman Reef to provide fuel, lodging, and meals.

[12][13] During the next several months, Pan Am successfully used the lagoon several times as a halfway station for its flying boats (Sikorsky S-42B) when they traveled between those two points.

The right outboard engine had developed an oil leak, and the aircraft burst into flames while dumping fuel; there were no survivors.

On February 14, 1941, President Franklin D. Roosevelt issued Executive Order 8682 to create naval defense areas in the central Pacific territories.

The proclamation established the "Kingman Reef Naval Defensive Sea Area", encompassing the territorial waters between the extreme high-water marks and the three-mile marine boundaries surrounding the atoll.

Only U.S. government ships and aircraft were permitted to enter the naval defense areas at Kingman Reef unless authorized by the Secretary of the Navy.

In 2012, Kingman Reef Atoll Development LLC, owned by descendants of the owners of the Palmyra Copra Co., Ltd., sued the U.S. government for its designation as a national wildlife refuge.

[20] For statistical purposes, Kingman Reef is grouped as part of the United States Minor Outlying Islands.

[23] The percentage of the total fish biomass on the reef is made up of 85% apex predators, creating a high level of competition for food and nutrients among local organisms – particularly sharks, jacks, and other carnivores.

[24] The threatened green sea turtles that frequent nearby Palmyra Atoll travel to Kingman Reef to forage and bask on the coral rubble spits at low tide.

Most flora that begin to grow above water—primarily coconut palms—die out quickly due to the fierce tides and lack of resources necessary to sustain plant life.

In January 2009, that entity was upgraded to the Pacific Remote Islands Marine National Monument by President George W.

[27] Between November 15, 1945, and March 28, 2016, Kingman Reef was considered a discrete entity to earn awards such as the DX Century Club.

[28] On March 28, 2016, the ARRL DXCC desk deleted Kingman Reef from the list of collectible entities[29] effective March 29, 2016, and deeming Kingman a part of the Palmyra and Jarvis entity due to proximity of the islands and common administration of the islands by the Fish and Wildlife Service.