By the end of 2012, 12 states and the District of Columbia had support for same-sex marriage at or above 50%. Of these 12 states, all currently perform marriages, civil unions, or domestic partnerships for same-sex couples. Thirteen additional states presently are within 5 percentage points of majority support. In the last eight years, every state has increased in its support for marriage for same-sex couples with an average increase of 13.6%. If present public opinion trends continue, another 8 states will be above 50% support by the end of 2014.
The obvious historical parallel is also interesting in this regard:
