The making of the United States

The Florida Cession, 1819

In 1810, when West Florida declared its independence from Spain, President James Madison sent in the troops. Spain did not accept this conquest until 1819, when the Adams-onís Treaty finally settled all American and Spanish claims in North America. Six months later, Spain annulled part of the treaty by recognising the independence of Mexico, creating new boundaries.

The Alaska Purchase, 1867

In 1867, Secretary of State William Seward signed the Alaska Purchase, in which the United States bought more than 885,000 square kilometres of territory in Alaska from the Russian Empire. The Russians, realising that Alaska was militarily indefensible, sold it for $7.2 million — about two cents an acre.

The Louisiana Purchase, 1803

In 1800, the French leader Napoleon Bonaparte tried to re-establish the French Empire in the Louisiana Territory. Three years later, the administration of President Thomas Jefferson bought the 1.3 million-square-kilometre territory from the French government for 50 million Francs ($11.25 million) and the cancellation of debts worth 18 million Francs ($3.75 million).

The Gadsden Purchase, 1853

In 1853, the United States paid $10 million to the Republic of Mexico for just over 48,000 square kilometres of territory in what is now southern Arizona and southwestern New Mexico. The US wanted land for a transcontinental railroad and the Mexican government needed money. The purchase was named for James Gadsden, the American ambassador to Mexico.

Treaty of Paris, 1783

The Treaty of Paris, in which Great Britain recognised the independence of its former American colonies, established the United States of America as 13 states, with an eastern border on the Atlantic Ocean and a northern border with British-ruled Canada. Its western border was the eastern bank of the Mississippi River.

Treaty of Guadalupe Hidaglo, 1848

Imposed on a defeated Mexico by the administration of President James Polk in the aftermath of the Mexican-american War, the Treaty of Guadalupe Hidalgo massively expanded the borders of the United States towards the Rio Grande, with the accession of Texas, and the Pacific Ocean, with the acquisition of California.