1 Jan 1913: 16th Amendment ratified,The 16th Amendment was ratified, allowing the federal government to collect an income tax.
1 Jan 1913: 17th Amendment ratified,The 17th Amendment was ratified, providing for the direct election of U.S. Senators.
2
1914
1 Jan 1914: Panama Canal opens,The Panama Canal officially opened, allowing ships to travel between the Atlantic and Pacific oceans.
3
1915
1 Jan 1915: Lusitania sinks,A German U-boat sank the British passenger liner Lusitania, killing 128 Americans and turning public opinion against Germany.