The more important turning points in public opinion, however, may be occurring at the state level, especially if states continue to control who can get married.

According to our research, as recently as 2004, same-sex marriage did not have majority support in any state. By 2008, three states had crossed the 50 percent line.

Today, 17 states are over that line (more if you consider the CNN estimate correct that just over 50 percent of the country supports gay marriage).

In 2008, the year Proposition 8 was approved, just under half of Californians supported same-sex marriage,. Today, according to polls, more than half do. A similar shift has occurred in Maine, where same-sex marriage legislation was repealed by ballot measure in 2009.