While most elections are in their own way historic, the election of 2012 may be a truly historic election (and one that will get it's own chapter in our history books, and not just a page or two) and regardless of what you may feel about the outcomes, there are several reasons why this election will most likely be considered historic.
Here are several reasons why I believe that this election will be considered in the future to be a truly historic one:
Three Presidents, six terms
For only the second time in this nation's history has there been three presidents in a row that have held two consecutive terms. The only other time this has happened was from 1801 to 1825 during the presidencies of Thomas Jefferson, James Madison, and James Monroe.
For the first time in our nation's history two candidates from two different minority groups (Barack Obama being African American, and Mitt Romney being a Mormon, a minority religion) have run for president under the two major political parties.
Light them up
Washington and Colorado became the first two states in the nation to legalize small amounts of marijuana for recreational use by adults. Of course this doesn't mean that it is completely legal (it is still illegal under federal law, and federal law enforcement agents can still arrest you if you have any pot on you) but it does mean that the local and state law enforcement in those two states can not arrest you if they find a bag of weed on you, or catch you smoking a joint.
The 51st State
For the first time in the island territory's history the people of Puerto Rico voted to become a state. Of course it doesn't mean that it will automatically become a state, as congress must vote on whether or not to approve statehood for the island. This could merely be a formality and could come as early as December, or this could be years from now.
If it does happen this year it will be the first time in 53 years that a new state has joined the United States.
Women in the Senate
There are now more women in the Senate then there have been at any other time in our history. There are now 20 women who are in the United States Senate, or 1/5 of the Senate.
For the first time in our history voters in several states approved legalizing same-sex marriage. In the states of Washington, Maryland, and Maine voters approved of a state laws that would legalize same-sex marriage (note: this is also significant because in 2009 it had been rejected in Maine), and in Minnesota voters rejected a state constitutional amendment that would outlaw same-sex marriage (mind you their state laws still outlaws it). Also, Tammy Baldwin of Wisconsin became the first homosexual to be elected to the Senate.