History Timeline By colewehling Jul 4, 1776 Formation of United States Period: Jan 1, 1783 to Jan 1, 1853 Westward Expansion Sep 3, 1783 Treaty of Paris Official Borders of US set Jul 4, 1803 Louisiana Purchase Sep 27, 1821 Mexican War of Independence Dec 30, 1853 Gadsden Purchase Period: Dec 24, 1892 to Dec 25, 1954 Ellis Island Open for Immigrants Period: Jul 28, 1914 to Nov 11, 1918 World War 1 May 24, 1924 Start of Border Patrol Jan 1, 1933 INS Formed Period: Sep 1, 1939 to Sep 2, 1945 World War 2 Dec 7, 1941 Attack on Pearl Harbor Period: Jan 1, 1980 to Jan 1, 1999 Massive Increase in Immigration Sep 11, 2001 9/11 Terrorist Attacks Mar 3, 2003 DHS takes over Border Protection
