US History By enterics Jul 4, 1776 Declaration of Independence: Jefferson Period: Jul 4, 1776 to May 9, 2012 US History Sep 17, 1787 Constitutional Convention Jan 1, 1789 George Washington:First president Jan 1, 1812 War of 1812 Jan 1, 1848 Mexican American War Jan 1, 1861 Civil War Abraham Lincoln Jan 1, 1898 Spanish American War Jan 1, 1914 World War I Woodrow Wilson Jan 1, 1929 Great Depression Jan 1, 1939 World War II; Franklin Roosevelt Jan 1, 1950 Korean War May 9, 1959 Vietnam War; Jan 1, 1990 Persian Gulf War