United States
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The United States of America, commonly known as the United States or America, is a country primarily located in North America. It is a federation of 50 states, a federal capital district, and 326 Indian reservations. Outside the union of states, it asserts sovereignty over five major unincorporated island territories and various uninhabited islands. The country has the world's third-largest land area, second-largest exclusive economic zone, and third-largest population, exceeding 334 million.
Cliff Palace, built by Ancestral Puebloans in present-day Montezuma County, Colorado, between c. 1200 and 1275
Declaration of Independence, a portrait by John Trumbull depicting the Committee of Five presenting the draft of the Declaration to the Continental Congress on June 28, 1776, in Philadelphia
Mikhail Gorbachev and Ronald Reagan sign the Intermediate-Range Nuclear Forces Treaty at the White House in 1987.
The Twin Towers in New York City during the September 11 attacks of 2001
Beringia
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Beringia is defined today as the land and maritime area bounded on the west by the Lena River in Russia; on the east by the Mackenzie River in Canada; on the north by 72 degrees north latitude in the Chukchi Sea; and on the south by the tip of the Kamchatka Peninsula. It includes the Chukchi Sea, the Bering Sea, the Bering Strait, the Chukchi and Kamchatka Peninsulas in Russia as well as Alaska in the United States and the Yukon in Canada.
The Last Glacial Period caused a much lower global sea level
The Mammut americanum (American mastodon) became extinct around 12,000–9,000 years ago due to human-related activities, climate change, or a combination of both. See Quaternary extinction event and Holocene extinction.