WASHINGTON, D.C. -- Americans' support for the law recognizing same-sex marriages as legally valid has increased yet again, now at 55%. Marriage equality advocates have had a string of legal successes over the past year, most recently this week in Pennsylvania and Oregon where federal judges struck down bans on gay marriage.

Two successive Gallup polls in 2012 saw support climb from 53% to 54%, indicating a steady but slight growth in acceptance of gay marriages over the past year after a more rapid increase between 2009 and 2011. In the latest May 8-11 poll, there is further evidence that support for gay marriage has solidified above the majority level. This comes on the heels of gay marriage proponents' 14th legal victory in a row.

When Gallup first asked Americans this question about same-sex marriage in 1996, 68% were opposed to recognizing marriage between two men or two women, with slightly more than a quarter supporting it (27%). Since then, support has steadily grown, reaching 42% by 2004 when Massachusetts became the first state to legalize it -- a milestone that reached its 10th anniversary this month.

In 2011, support for gay marriage vaulted over the 50% mark for the first time, and since 2012, support has remained above that level. In the last year, however, support has leveled off a bit. Currently, 17 states and the District of Columbia have legalized same-sex marriage, while several states wait in legal limbo as they appeal judge rulings overturning state bans.

Among the most dramatic divisions in opinion on the issue are between age groups. As has been the case in the past, support for marriage equality is higher among younger Americans; the older an American is, the less likely he or she is to support marriage for same-sex couples. Currently, adults between the ages of 18 and 29 are nearly twice as likely to support marriage equality as adults aged of 65 and older.

Opinions also differ dramatically along party lines. Democrats (74%) are far more likely to support gay marriage as Republicans are (30%), while independents (58%) are more in line with the national average. Though Republicans still lag behind in their support of same-sex marriage, they have nearly doubled their support for it since Gallup began polling on the question in 1996.

An important region on the radar of gay marriage advocates is the South, where a condensed cluster of bans on same-sex marriage exists. All southern states have constitutional bans on same-sex marriage, from Louisiana in 2004 through North Carolina in 2012, though bans have been challenged in Arkansas and Kentucky. The South (48%) is the only region where same-sex marriage support falls below the 50% mark. Support is highest in the East, where two-thirds (67%) of residents support gay marriage.

Bottom Line

For proponents of marriage equality, years of playing offense have finally paid off as this movement has reached a tipping point in recent years -- both legally and in the court of public opinion. The latest gains are in Pennsylvania and Oregon, with court challenges in Utah, Oklahoma, and Virginia likely to be determined soon. Having spent years trying to influence state lawmakers to take action, gay marriage supporters' game strategy has officially pivoted to challenging state bans in court. One key question in the legal battle is the constitutionality of voter-approved state bans.

Younger Americans are more supportive of same-sex marriage, and this will likely continue to drive overall support at the gradual pace it has increased over recent years. While the map of gay marriage is regionally diverse, it is not so in the South, where traditional marriage advocates still hold a majority of support. Public opinion in southern states will be a barometer to observe, as the bulk of future legal battles will play out there in the months and years to come.