The United States of America (USA) is a federal constitutional republic made up of 50 states (48 continental states, plus Alaska and Hawaii the two newest states) and one federal district - Washington, D.C., the capital district. The USA is washed by the Atlantic Ocean in the east and by the Pacific Ocean in the west. The mainland United States borders Canada to the north and Mexico to the south.
The place where is now the United States has been inhabited since prehistoric times by Native American tribes called Indians.
The first English colony was founded at Jamestown, Virginia, in 1607. On July 4, 1776 thirteen colonies of Great Britain declared the independence of a nation called "the United States of America" in the Declaration of Independence, primarily authored by Thomas Jefferson. George Washington -
a renowned hero of the American Revolutionary War - became the first President of the United States under the new U.S. Constitution. The nation's birthday is celebrated on the 4th July. During the
19th and 20th centuries, 37 new states were
added to the original 13 as the nation expanded across the North American continent.
The United States has a total area of 3,676,487 square miles (9,522,057 square kilometers). The population of the USA was estimated at 335,770,734 (est. Aug. 2017). USA is 230 times bigger than Switzerland and has 40 times bigger population.