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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 Geological Survey (USGS), founded as the Geological Survey, is an agency of the U.S. Department of the Interior whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on March 3, 1879, to study the landscape of the United States, its natural resources, and the natural hazards ...
The physiographic regions of the contiguous United States comprise 8 divisions, 25 provinces, and 85 sections. [1] The system dates to Nevin Fenneman 's report Physiographic Divisions of the United States, published in 1916. [2] [3] The map was updated and republished by the Association of American Geographers in 1928. [4]
April 15, 1931 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 ...
The Grand Canyon, carved by the mighty Colorado River, is 277 miles (446 km) long, up to 1 mile (1.6 km) deep, and up to 15 miles (24 km) wide. Millions of years of erosion have resulted in a massive three-tiered canyon, exposing the multicolored layers of the Colorado Plateau in mesas and canyon walls, visible from trails that descend into the ...
The inland and intracoastal waterways of the eastern United States. The inland waterways of the United States include more than 25,000 mi (40,000 km) of navigable waters. Much of the commercially important waterways of the United States consist of the Mississippi River System —the Mississippi River and connecting waterways.
The Mississippi drainage basin includes the Missouri and the Mississippi rivers, the two longest main-stem rivers in the United States, as well as 18 more of the rivers on this list. The Mississippi main stem is highlighted in dark blue. The longest rivers of the United States include 38 that have main stems of at least 500 miles (800 km) long.