UPDATED FEBRUARY 16, 2012, WITH MORE COMPLETE DATA.

As courts and legislatures address the question of whether same-sex couples should be allowed to legally marry, public support for gay marriage continues to grow. Polls in 2011 by the Pew Research Center for the People & the Press found that an average of 46% favor allowing gays and lesbians to marry legally; about the same percentage (45%) opposes gay marriage. That marked the first time in 15 years of polling that the public has been evenly divided over this issue.

Just two years earlier, in 2009, a clear majority (54%) opposed gay marriage while just 37% favored it. In 1996, when Pew Research first asked about letting gay couples marry legally, almost two-thirds of the public (65%) opposed the idea, and just 27% favored it.

There continue to be substantial generational, partisan and racial differences over gay marriage. Since the 1990s, however, support has increased across most demographic and political groups.

The shift in opinion has been driven in no small part by generational change. Millennials (born after 1980) are the most in favor of gay marriage (61% favor), followed by Gen Xers, born between 1965 and 1980 (48%). There is somewhat less support among Baby Boomers (40%), born 1946 to 1964, and members of the Silent Generation (32%), born 1928 to 1945.

A majority of Democrats (56%) favor allowing gays and lesbians to marry legally, as do 51% of independents. By comparison, just 27% of Republicans favor same-sex marriage while 66% are opposed. In recent years, support for gay marriage has risen sharply among Democrats and independents, while Republicans’ views have shown less change.

Both whites and blacks have become more likely to favor marriage rights for gays in recent years, but the increase in support has been larger among whites. In 2011, 49% off whites and 36% of blacks said they favored allowing gay and lesbian couples to marry legally.

(For more on attitudes of religious groups toward gay marriage, see “Religion and Attitudes toward Same-Sex Marriage,” Pew Forum on Religion & Public Life, Feb. 7, 2012.)

Most Say Homosexuality Should Be Accepted

Since the 1990s, there also has been an increase in the percentage of Americans saying that homosexuality should be accepted by society. In March 2011, 58% said that homosexuality should be accepted by society, while a third (33%) said it should be discouraged.

In 1994 and 1995, when the Pew Research Center first began asking about this topic, opinion was about evenly divided. But by 2000, slightly more said homosexuality should be accepted by society than said it should be discouraged (50% vs. 41%).

In 2006, 51% said homosexuality should be accepted, while 38% said it should be discouraged. In 2011, support for societal acceptance of homosexuality again increased, to 58%.