The United States of America (commonly referred to as the United States, the U.S., the USA, or America) is a federal The structure of federal governments vary from institution to institution based on a broad definition of a basic federal political system, there are two or more levels of government that exist within an established territory and govern through common institutions with overlapping or shared powers as prescribed by a constitution constitutional republic A constitutional republic is a state where the head of state and other officials are elected as representatives of the people, and must govern according to existing constitutional law that limits the government's power over citizens. In a constitutional republic, executive, legislative, and judicial powers are separated into distinct branches and comprising fifty states A U.S. state is any one of 50 subnational entities of the United States of America that share sovereignty with the federal government . Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. However, state citizenship is very flexible, and no government approval is required to and a federal district Federal districts are a type of administrative division of a federation, under the direct control of the federal government. The country is situated mostly in central North America North America is the northern continent of the Americas, situated in the Earth's northern hemisphere and almost totally in the western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the west by the North Pacific Ocean; South America lies to the, where its forty-eight contiguous states The term contiguous United States refers to the 48 U.S. states located on the North American continent south of the border with Canada, plus the District of Columbia. The term excludes the states of Alaska and Hawaii and all off-shore U.S. territories and possessions and Washington, D.C. Washington, D.C. , formally the District of Columbia and commonly referred to as Washington, the District, or simply D.C., is the capital of the United States, founded on July 16, 1790. The City of Washington was originally a separate municipality within the Territory of Columbia until an act of Congress in 1871 effectively merged the City and the, the capital district A capital territory or capital district is normally a specially designated administrative division where a country's seat of government is located. As such, in the federal model of government, no one state or territory takes pre-eminence because the national capital lies within its borders. A capital territory can be a specific form of federal, lie between the Pacific The Pacific Ocean is the largest of the Earth's oceanic divisions. Its name is derived from the Latin name Mare Pacificum, "peaceful sea", bestowed upon it by the Portuguese explorer Ferdinand Magellan. It extends from the Arctic in the north to Antarctica in the south, bounded by Asia and Australia in the west, and the Americas in the and Atlantic Oceans The Atlantic Ocean is the second-largest of the world's oceanic divisions; with a total area of about 106.4 million square kilometres . It covers approximately one-fifth of the Earth's surface. The first part of its name refers to the Atlas of Greek mythology, making the Atlantic the "Sea of Atlas". The oldest known mention of this name, bordered Categories: Borders of the United States | Geography of the United States by Canada Canada is a country occupying most of upper North America, extending from the Atlantic Ocean in the east to the Pacific Ocean in the west and northward into the Arctic Ocean. It is the world's second largest country by total area and shares the world's longest common border with the United States to the south and northwest to the north and Mexico The United Mexican States (Spanish: Estados Unidos Mexicanos ), commonly known as Mexico (English: /ˈmɛksɪkoʊ/) (Spanish: México (help·info) [ˈmexiko]), is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, to the south. The state of Alaska Alaska ( /əˈlæskə/ , Russian: Аляска Alyaska) is the largest state of the United States of America by area; it is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait is in the northwest of the continent, with Canada to its east and Russia Russia (pronounced /ˈrʌʃə/ ; Russian: Россия, pronounced [rʌˈsʲijə]), officially known as both Russia and the Russian Federation(Russian: Российская Федерация​ (help·info), Rossiyskaya Federatsiya), is a country in northern Eurasia (Europe and Asia together). It is a semi-presidential republic, comprising 83 to the west across the Bering Strait The Bering Strait is a sea strait between Cape Dezhnev, Chukotka Autonomous Okrug, the easternmost point (169°43' W) of the Asian continent and Cape Prince of Wales, Alaska, the westernmost point (168°05' W) of the North American continent, with latitude of about 65° 40' north, slightly south of the polar circle. It is one of the biggest of its. The state of Hawaii The State of Hawaii ( /həˈwaɪ.iː/ or /həˈwaɪʔiː/ in English; Hawaiian: Mokuʻāina o Hawaiʻi) is a state in the United States, located on an archipelago in the central Pacific Ocean southwest of the continental United States, southeast of Japan, and northeast of Australia. The state was admitted to the Union on August 21, 1959, making it is an archipelago An archipelago is a chain or cluster of islands that are formed tectonically. The word archipelago literally means "chief sea", from Italian arcipelago (artʃiˈpelaɡo), derived ultimately from Greek arkhon (arkhi-) ("leader") and pelagos ("sea"). In Italian, possibly following a tradition of antiquity, the in the mid-Pacific. The country also possesses several territories Territories of the United States are one type of political division of the United States, administered by the U.S. government but not any part of a U.S. state. These territories were created to govern newly acquired land while the borders of the United States were still evolving. Territories can be classified by whether they are incorporated and, or insular areas An insular area is a United States territory, that is neither a part of one of the fifty U.S. states nor the District of Columbia, the federal district of the United States, in the Caribbean The Caribbean (pronounced /ˌkærɨˈbiːən/ or /kəˈrɪbiən/; Dutch Caraïben ; French: Caraïbe or more commonly Antilles; Spanish: Caribe) is a region consisting of the Caribbean Sea, its islands (most of which enclose the sea), and the surrounding coasts. The region is located southeast of the Gulf of Mexico and Northern America, east of and Pacific.

At 3.79 million square miles (9.83 million km²) and with about 306 million people, the United States is the third or fourth This is a list of the sovereign states and dependent territories of the world, sorted by total area, including all entities on the ISO standard ISO 3166-1 largest country by total area, and third largest by land area and by population This is a list of countries ordered according to population. The list includes sovereign states and inhabited dependent territories based on the ISO standard ISO 3166-1. The United States is one of the world's most ethnically diverse Multiethnic societies, in contrast to ethnically homogenous societies, integrate different ethnic groups irrespective of differences in culture, race, and history under a common social identity larger than one "nation" in the conventional sense. All cities and most towns can be regarded as multiethnic societies, even ones where race and multicultural The term multiculturalism generally refers to the acceptance of various cultural divisions for the sake of diversity that applies to the demographic make-up of a specific place, usually at the scale of an organization such as a school, business, neighborhood, city or nation nations, the product of large-scale immigration from many countries American immigration refers to the movement of non-residents to the United States. Immigration has been a major source of population growth and cultural change throughout much of American history. The economic, social, and political aspects of immigration have caused controversy regarding ethnicity, religion, economic benefits, job