Britain's American colonies broke with
the mother country in 1776 and were recognized as the
new nation of the United States of America following
the Treaty of Paris in 1783. During the 19th and 20th
centuries, 37 new states were added to the original
13 as the nation expanded across the North American
continent and acquired a number of overseas possessions.
The two most traumatic experiences in the nation's history
were the Civil War (1861-65) and the Great Depression
of the 1930s. Buoyed by victories in World Wars I and
II and the end of the Cold War in 1991, the US remains
the world's most powerful nation-state. The economy
is marked by steady growth, low unemployment and inflation,
and rapid advances in technology.