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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 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 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 ...
Watersheds of North America. A map of watersheds separated by the principal hydrological divides of North America. Watersheds of North America are large drainage basins which drain to separate oceans, seas, gulfs, or endorheic basins. There are six generally recognized hydrological continental divides which divide the continent into seven ...
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 ...
Metrication in the United States. A shampoo label from the U.S. that shows a round metric quantity taking secondary status in parentheses next to non-integer U.S. customary quantity. Metrication (or metrification) is the process of introducing the International System of Units, also known as SI units or the metric system, to replace a ...
Two rivers, the Colorado and the Rio Grande, begin in the United States and flow into or form a border with Mexico. [5] In addition, the drainage basins of the Mississippi and Missouri rivers extend into Canada, [6] [7] and the basin of the Gila River extends into Mexico. [8] Sources report hydrological quantities with varied precision.
The state with the most national parks is California with nine, followed by Alaska with eight, Utah with five, and Colorado with four. The largest national park is Wrangell–St. Elias in Alaska: at over 8 million acres (32,375 km 2), it is larger than each of the nine smallest states.