President Obama announced his support for gay marriage this week after a long consideration saying his views were "evolving." The public's view of gay marriage has changed over the past several decades, with growing support.
In 2001, Americans opposed same-sex marriage by a 57% to 35% margin. Today, the public is about evenly split, with 47% in favor and 43% opposed.
This is due in part to generational change. Younger generations express higher levels of support for same-sex marriage. In 2012 Pew Research Center polling, Millennials are twice as likely as the Silent Generation to support same-sex marriage.
View an interactive graphic that illustrates these trends in public opinion: Changing Attitudes on Gay Marriage.