Territorial evolution of the United States in the context of "America"

The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 states and a federal capital district, Washington, D.C. The 48 contiguous states border Canada to the north and Mexico to the south, with the semi-exclave of Alaska in the northwest and the archipelago of Hawaii in the Pacific Ocean. The United States also asserts sovereignty over five major island territories and various uninhabited islands in Oceania and the Caribbean. It is a megadiverse country, with the world's third-largest land area and third-largest population, exceeding 340 million.

Paleo-Indians first migrated from North Asia to North America over 12,000 years ago, and formed various civilizations. Spanish colonization established Spanish Florida in 1513, the first European colony in what is now the continental United States. British colonization followed with the 1607 settlement of Virginia, the first of the Thirteen Colonies. Enslavement of Africans was practiced in all colonies by 1770 and supplied most of the labor for the Southern Colonies' plantation economy. Clashes with the British Crown over taxation and lack of parliamentary representation sparked the American Revolution, leading to the Declaration of Independence on July 4, 1776. Victory in the 1775–1783 Revolutionary War brought international recognition of U.S. sovereignty and fueled westward expansion, dispossessing native inhabitants. As more states were admitted, a North–South division over slavery led the Confederate States of America to attempt secession and fight the Union in the 1861–1865 American Civil War. With the United States' victory and reunification, slavery was abolished nationally. By 1900, the country had established itself as a great power, a status solidified after its involvement in World War I. Following Japan's attack on Pearl Harbor in 1941, the U.S. entered World War II. Its aftermath left the U.S. and the Soviet Union as rival superpowers, competing for ideological dominance and international influence during the Cold War. The Soviet Union's collapse in 1991 ended the Cold War, leaving the U.S. as the world's sole superpower.

The United States Armed Forces are the military forces of the United States. U.S. federal law names six armed forces: the Army, Marine Corps, Navy, Air Force, Space Force, and Coast Guard. Since 1949, all of the armed forces, except the Coast Guard, have been permanently part of the United States Department of Defense, with the Space Force existing as a branch of the Air Force until 2019. They form six of the eight uniformed services of the United States.

From their inception during the American Revolutionary War, the Army and the Navy, and later the other services, have played a decisive role in the country's history. They helped forge a sense of national unity and identity through victories in the early-19th-century First and Second Barbary Wars. They played a critical role in the territorial evolution of the U.S., including the American Civil War. The National Security Act of 1947 created the Department of Defense or DoD, (after a short period being called the National Military Establishment) headed by the secretary of defense, superior to the service secretaries. It also created both the U.S. Air Force and National Security Council; in 1949, an amendment to the act merged the cabinet-level departments of the Army, Navy, and Air Force into the DoD.

The Republic of Texas (Spanish: República de Tejas), or simply Texas, was a sovereign country in North America from March 2, 1836, to February 19, 1846. Texas was bordered by Mexico to the west and southwest, the Gulf of Mexico to the southeast, the two U.S. states of Louisiana and Arkansas to the east and northeast, and U.S. unorganized territory encompassing parts of the current U.S. states of Oklahoma, Kansas, Colorado, and Wyoming to the north. The Texas Revolution began when hostilities broke out on October 2, 1835, shortly before the regime of Mexican President and General Antonio López de Santa Anna adopted a new Mexican constitution known as the Siete Leyes that abolished the authority of the states under the federal republic and established a centralized government. The revolution lasted for over six months. On March 2, 1836, delegates in convention proclaimed the Texas Declaration of Independence. Major fighting ended on April 21, 1836, with the Treaties of Velasco that ended the fighting and secured Texas' independence.

The Mexican Congress refused to recognize the independence of the Republic of Texas, as the Treaties of Velasco were signed by Santa Anna under duress as prisoner. The majority of the Mexican Congress did not approve the agreement. Much of its territory was controlled and disputed by Mexico or the Comancheria; Mexico considered it a rebellious province during its entire existence. The Anglo-American residents of the area and of the republic were referred to as Texians, while Texans of Mexican descent were referred to as Tejanos.

The Indian removal was the United States government's policy of ethnic cleansing through the forced displacement of self-governing tribes of American Indians from their ancestral homelands in the eastern United States to lands west of the Mississippi River—specifically, to a designated Indian Territory (roughly, present-day Oklahoma), which many scholars have labeled a genocide. The Indian Removal Act of 1830, the key law which authorized the removal of Native tribes, was signed into law by United States president Andrew Jackson on May 28, 1830. Although Jackson took a hard line on Indian removal, the law was primarily enforced during the Martin Van Buren administration, 1837 to 1841. After the enactment of the Act, approximately 60,000 members of the Cherokee, Muscogee (Creek), Seminole, Chickasaw, and Choctaw nations (including thousands of their black slaves) were forcibly removed from their ancestral homelands, with thousands dying during the Trail of Tears.

Indian removal, a popular policy among incoming settlers, was a consequence of actions first by the European colonists and then later on by the American settlers in the nation during the thirteen colonies and then after the revolution, in the United States of America also until the mid-20th century.

Fort Leavenworth (/ˈlɛvənˌwɜːrθ/) is a United States Army installation located in Leavenworth County, Kansas, in the city of Leavenworth. Built in 1827, it is the second oldest active United States Army post west of Washington, D.C., and the oldest permanent settlement in Kansas. Fort Leavenworth has been historically known as the "Intellectual Center of the Army."

During the country's westward expansion, Fort Leavenworth was a forward destination for thousands of soldiers, surveyors, immigrants, American Indians, preachers and settlers who passed through.