Events in 1912
Arizona
Arizona: Admitted as a state on 14 Feb 1912, the last of the 48 mainland states to join the union. The governor is George WP Hunt, Democrat.
The United States
President: William Howard Taft, a Republican, approaching the end of his first term. His accomplishments include civil service reform, trust-busting, introducing corporate income taxes, and getting the 16th Amendment (allowing federal income taxes) passed. Later this year he's going to lose the election to Democrat Woodrow Wilson in a four-way race that also includes Progressive Teddy Roosevelt and Socialist Eugene Debs.
The 17th Amendment, establishing that US Senators are elected directly by the people of their states, and not by state legislatures, is introduced into Congress in May 1912, but doesn't pass until 1913. This is a pretty popular issue; it's widely believed that senatorial elections are bought and sold for favors and money.