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Geology of the United States. Shaded relief map of the United States, showing 10 geological provinces. The richly textured landscape of the United States is a product of the dueling forces of plate tectonics, weathering and erosion. Over the 4.5 billion-year history of the Earth, tectonic upheavals and colliding plates have raised great ...
The term "United States," when used in the geographical sense, refers to the contiguous United States (sometimes referred to as the Lower 48, including the District of Columbia not as a state), Alaska, Hawaii, the five insular territories of Puerto Rico, Northern Mariana Islands, U.S. Virgin Islands, Guam, American Samoa, and minor outlying possessions. [1]
The United States expropriated from Panama additional areas around the soon-to-be-built Madden Dam and annexed them to the Panama Canal Zone. [363] [371] Caribbean Sea: May 3, 1932 The United States adjusted the border at Punta Paitilla in the Canal Zone, returning a small amount of land to Panama. This was the site for a planned new American ...
The United States is a major exporter of agricultural products. The southern portion of the Great Plains lies over the Ogallala Aquifer , a huge underground layer of water-bearing strata. Center pivot irrigation is used extensively in drier sections of the Great Plains, resulting in aquifer depletion at a rate that is greater than the ground's ...
Geologic map of North America. The geology of North America is a subject of regional geology and covers the North American continent, the third-largest in the world. Geologic units and processes are investigated on a large scale to reach a synthesized picture of the geological development of the continent. The divisions of regional geology are ...
The Missouri River is a river in the Central and Mountain West regions of the United States.The nation's longest, [13] it rises in the eastern Centennial Mountains of the Bitterroot Range of the Rocky Mountains of southwestern Montana, then flows east and south for 2,341 miles (3,767 km) [9] before entering the Mississippi River north of St. Louis, Missouri.
Territories of the United States. Territories of the United States are sub-national administrative divisions overseen by the federal government of the United States. The American territories differ from the U.S. states and Indian reservations as they are not sovereign entities. [note 2] In contrast, each state has a sovereignty separate from ...
The cartography of the United States is the history of surveying and creation of maps of the United States. Maps of the New World had been produced since the 16th century. The history of cartography of the United States begins in the 18th century, after the declared independence of the original Thirteen Colonies on July 4, 1776, during the ...