The United States is the world's foremost economic and military power, with global interests and an unmatched global reach. In 1492 Christopher Columbus arrived in North America. Following early explorations by Portugal and Spain, England established a colony at Jamestown, Virginia, in 1607. Thirteen British colonies waged a war of independence against England from 1775 to 1783, when the new nation of the United States of America was recognized by the Treaty of Paris. 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 constitution, drafted in 1787, established a federal system with a division of powers which has remained unchanged in form since its inception. The two most traumatic experiences in the nation's history were the Civil War (1861-65), in which a northern Union of states defeated a secessionist Confederacy of 11 southern slave states, and the Great Depression of the 1930s, an economic downturn during which about a quarter of the labor force lost its jobs. The real recovery came only during World War II that stimulated the nation’s industry and the economy in general. The United States today remains the world's most powerful country. Its economy is the largest and most technologically advanced in the world. The country has the highest level of output in the world, with its gross domestic product accounting for close to a quarter of the world total.