United States elections, 2012
The U.S. territory of Puerto Rico votes to become a U.S. state. If previous procedure is followed, Congress will now request that Puerto Rico establish a state constitution. Then, Congress would vote to approve it as a state, which it usually does. However, Congress is not obligated to follow this procedure, and by its vote, it ultimately must decide, which is not yet certain. Obama and Romney had both pledged to support the result of the referendum and to work with Congress on the issue.
Sources: BBC