At 3.8 million square miles (9.842 million km2) and with over 320 million people, the country is the world's third or fourth-largest by total area and the third most populous.
It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many countries.
Paleo-Indians migrated from Eurasia to what is now the U.S. mainland at least 15,000 years ago, with European colonization beginning in the 16th century.
The United States is a developed country and has the world's largest national economy by nominal and real GDP, benefiting from an abundance of natural resources and high worker productivity.
While the U.S. economy is considered post-industrial, the country continues to be one of the world's largest manufacturers.
On July 4, 1776, as the colonies were fighting Great Britain in the American Revolutionary War, delegates from the 13 colonies unanimously adopted the Declaration of Independence. The war ended in 1783 with recognition of the independence of the United States by the Kingdom of Great Britain, and was the first successful war of independence against a European colonial empire. The country's constitution was adopted on September 17, 1787, and ratified by the states in 1788. The first ten amendments, collectively named the Bill of Rights, were ratified in 1791 and designed to guarantee many fundamental civil liberties.
This involved displacing American Indian tribes, acquiring new territories, and gradually admitting new states, until by 1848 the nation spanned the continent.
The end of the Cold War and the dissolution of the Soviet Union in 1991 left the United States as the world's sole superpower.
- United States has largest boundary with Canada which is approximately 8893 km .
- The largest river in United States is Missouri River which is 4090 km.
- The largest export partner of United States is Canada.
- The largest import partner of United States is China.
- There are 885 seaports in United States.
Surprising facts about Nobel Prize winners#
- United States has largest number of Nobel Prize winners (counting who was born in United States) in all areas except literature (in literature it is France)
- United States has largest number of women Nobel Prize winners (11). (Counting women born in United States)
- Elinor Ostrom is the first woman Nobel Prize winner in economics in year 2009. She was born in United States.
- Carl David Anderson is a United States born Nobel Prize winner who got the Nobel Prize quite early, at the age of 31 years.
Tourist Attraction#The Colorado River winds through Nankoweap Canyon in Grand Canyon National Park, Arizona.
- The national bird of United States is Bald eagle.
- The Rose is the national flower of United States
- The Square dance "dance of four couples" usually associated with United States.
- Text marked as italic is taken from https://en.wikipedia.org/wiki/United States