<P> The date of the start of the history of the United States is a subject of debate among historians . Older textbooks start with the arrival of Christopher Columbus on October 12, 1492 and emphasize the European background of the colonization of the Americas, or they start around 1600 and emphasize the American frontier . In recent decades American schools and universities typically have shifted back in time to include more on the colonial period and much more on the prehistory of the Native Americans . </P> <P> Indigenous people lived in what is now the United States for thousands of years before European colonists began to arrive, mostly from England, after 1600 . The Spanish built small settlements in Florida and the Southwest, and the French along the Mississippi River and the Gulf Coast . By the 1770s, thirteen British colonies contained two and a half million people along the Atlantic coast east of the Appalachian Mountains . After the end of the French and Indian Wars in the 1760s, the British government imposed a series of new taxes, rejecting the colonists' argument that any new taxes had to be approved by them (see Stamp Act 1765). Tax resistance, especially the Boston Tea Party (1773), led to punitive laws (the Intolerable Acts) by Parliament designed to end self - government in Massachusetts . American Patriots (as they called themselves) adhered to a political ideology called republicanism that emphasized civic duty, virtue, and opposition to corruption, fancy luxuries and aristocracy . </P> <P> Armed conflict began in 1775 as Patriots drove the royal officials out of every colony and assembled in mass meetings and conventions . In 1776, the Second Continental Congress declared that there was a new, independent nation, the United States of America, not just a collection of disparate colonies . With large - scale military and financial support from France and the military leadership of General George Washington, the American Patriots won the Revolutionary War . The peace treaty of 1783 gave the new nation the land east of the Mississippi River (except Florida and Canada). The central government established by the Articles of Confederation proved ineffectual at providing stability, as it had no authority to collect taxes and had no executive officer . Congress called a convention to meet secretly in Philadelphia in 1787 . It wrote a new Constitution, which was adopted in 1789 . In 1791, a Bill of Rights was added to guarantee inalienable rights . With Washington as the first president and Alexander Hamilton his chief political and financial adviser, a strong central government was created . When Thomas Jefferson became president he purchased the Louisiana Territory from France, doubling the size of the United States . A second and final war with Britain was fought in 1812 . </P> <P> Encouraged by the notion of manifest destiny, federal territory expanded all the way to the Pacific . The U.S. always was large in terms of area, but its population was small, only 4 million in 1790 . Population growth was rapid, reaching 7.2 million in 1810, 32 million in 1860, 76 million in 1900, 132 million in 1940, and 321 million in 2015 . Economic growth in terms of overall GDP was even faster . However, compared to European powers, the nation's military strength was relatively limited in peacetime before 1940 . The expansion was driven by a quest for inexpensive land for yeoman farmers and slave owners . The expansion of slavery was increasingly controversial and fueled political and constitutional battles, which were resolved by compromises . Slavery was abolished in all states north of the Mason--Dixon line by 1804, but the South continued to profit off the institution, producing high - value cotton exports to feed increasing high demand in Europe . The 1860 presidential election of Republican Abraham Lincoln was on a platform of ending the expansion of slavery and putting it on a path to extinction . </P>

When did america become known as the united states