Territorial evolution of the United States
The United States of America was formed after thirteen British colonies in North America declared independence from the British Empire on July 4, 1776. In the Lee Resolution, passed by the Second Continental Congress two days prior, the colonies resolved that they were free and independent states. The union was formalized in the Articles of Confederation, which came into force on March 1, 1781, after being ratified by all 13 states. Their independence was recognized by Great Britain in the Treaty of Paris of 1783, which concluded the American Revolutionary War. This effectively doubled the size of the colonies, now able to stretch west past the Proclamation Line to the Mississippi River. This land was organized into territories and then states, though there remained some conflict with the sea-to-sea grants claimed by some of the original colonies. In time, these grants were ceded to the federal government.
An example of a banco, created when a meander is cut off by a new, shorter channel, leaving a cut-off section of land surrounded by a U-shaped (oxbow) lake
The United States of America, commonly known as the United States or America, is a country primarily located in North America. It is a federation of 50 states, a federal capital district, and 326 Indian reservations. Outside the union of states, it asserts sovereignty over five major unincorporated island territories and various uninhabited islands. The country has the world's third-largest land area, second-largest exclusive economic zone, and third-largest population, exceeding 334 million.
Cliff Palace, built by Ancestral Puebloans in present-day Montezuma County, Colorado, between c. 1200 and 1275
Declaration of Independence, a portrait by John Trumbull depicting the Committee of Five presenting the draft of the Declaration to the Continental Congress on June 28, 1776, in Philadelphia
Mikhail Gorbachev and Ronald Reagan sign the Intermediate-Range Nuclear Forces Treaty at the White House in 1987.
The Twin Towers in New York City during the September 11 attacks of 2001