United States began as 13 rebellious colonies along the east coast, in the middle of the North American continent. Today, the United States of America (USA) is a federation of 50 states, a federal district – Washington D.C., the capital of the nation- as well as five major territories and various possessions. The 48 contiguous states share sovereignty with the federal government, while the territories are sub-national administrative divisions, overseen by the federal government - but self-governed with locally elected governors and territorial legislatures. It is the world's third-largest country by size -after Russia and Canada- and by population -after China and India.
Located in North America, US geographical features have operated as a natural border with the neighbours. The Atlantic and Pacific oceans ‘insulate’ the US from Asia and Europe, while deserts separate the US from Mexico –to the south- and lakes and forests separate the US from Canada –to the north. Varying greatly on area and local topography, the distinct network of easily navigable rivers, the extensive hydrological engineering at lakes and the natural deep-water ports, have helped towards the development of the region as an economic and political power.
The two world wars greatly impacted all of the powers that got involved in them. However, no battles were fought in the mainland United States, neither a single American factory was ever bombed. Alone among the world's powers in 1945, the United States was not only functional, but thriving. The two world wars helped the United States to clear away the competition and thrive at that period. Since then, the economy has achieved relatively steady growth, low unemployment and inflation, and rapid advances in technology.
The US have a diverse population of 318.9 million (2014) -primarily coming from various Western European states- having as a primary language English, followed by Spanish and various other Indo-European dialects.