United States Timeline
1783 Great Britain acknowledges American independence in the Treaty of Paris, formally ending the Revolutionary War.
1785 The Northwest Ordinance was the first of over 300 laws passed by the federal government to help encourage settlement, to survey the land, and to establish a legal record-keeping system. The rectangular survey system was established dividing most of the land in the public domain into townships and sections.
1803 The Louisiana Purchase: 885,000 square miles of land between the Mississippi River and the Rocky Mountains that the United States purchased from France.
1819 Spain ceded the remainder of West Florida and all of East Florida to the United States.
1823 Monroe Doctrine: President James Monroe declared that the American continents were off limits for further colonization by European powers—later justifying U.S. imperialism in the Western Hemisphere.
'1'845 Manifest Destiny: The popular notion that the United States was "destined" to expand from the Atlantic Ocean to the Pacific Ocean.
1846 Oregon Treaty: The border of Canada and the United States was established at the 49th parallel and the U.S. acquired the Oregon Territory.
1846-1848 The Mexican War was fought between the United States and Mexico over U.S. expansion. At the end of the war, a treaty gave the U.S. land extending from Oklahoma to California (now California, Nevada, Utah, and parts of Arizona, Colorado, New Mexico, and Wyoming).
1862 Homestead Act: Land was distributed after 1862 to homesteaders who could receive a patent (title) to the land by residing on it and making improvements for five years. Subsequent laws modified the requirements and the amount of land one could obtain by homesteading.
1865The ending of the Civil War opened opportunities for land ownership—especially west of the Missouri River.
1867The United States purchased Alaska from Russia. 1869 The first trans-continental railroad was completed.
1898The end of the Spanish-American War brought Puerto Rico, Guam, and the Philippines under the control of the United States.
1898The United States annexed Hawaii.
1899 The United States acquired American Samoa.
1903 The United States acquired the Panama Canal Zone.
1916 The United States acquired the Virgin Islands (formerly the Danish West Indies).
1946 The Philippines became and independent republic.
1952 Puerto Rico became a commonwealth of the United States.
1979 Panama took control of the Canal Zone.