By Global Public Square staff

As the Supreme Court ponders the legality of gay marriage in the United States, everyone is talking about the political divide, where twice as many Democrats support gay marriage as Republicans. The more influential divide is actually not a simple left or right...it's age.

A chart from the Pew Research Center shows that of Americans born in the 1930's and '40s (known as the "Silent Generation") only 31 percent favor same-sex marriage. But amongst baby boomers, the number rises to 38 percent. It gets still higher for the middle-aged "Generation X", at about 49 percent. For the Millennials, those born in 1981 or later: 70 percent support gay marriage. Some other polls put that number even higher, rising to 80 percent.

Millennials are an important constituency, representing about a fifth of this country's voting-age population. Obviously, they are going to be around longer than anyone else, so you want to have them on your side.

And their voting patterns are actually striking. If you break down voter's party choices by age groups, here's what you find. The oldest generation breaks Republican 48 to 44 percent, the baby boomers break democratic by about the same margin, the generation after that, Generation X, is slightly Democratic by 47 to 45 percent. The Millenials, however, are off the charts – they are Democratic by 62 to 30 percent in 2008 and 55 to 36 percent in 2012. This is a stunning gap.

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Now, some explain this by citing a common myth: when you're young, you're liberal; the older you get, the more conservative you become. But it turns out the most important factor is not just your age, but when you came of age.

The Pew Research Center data also shows that Americans who turned 18 during the Obama or George W. Bush years have overwhelmingly supported Democrats in every presidential election they've voted in. The same goes for those who came of age during the Clinton years – they are Democrats. But that doesn't mean young Americans have always skewed left.

Look back at the Republican-led years of Reagan and George H. W. Bush and the numbers look very different: Americans who came of age then have skewed Republican in the polls ever since. The same goes for the Ford and Carter years.

So what can we infer about the present?

For now, Democrats have a lock on the young demographic. The party has been more progressive on many of the issues dear to young Americans: immigration, gay marriage, gun control.

On the other hand, these are historically bad times for the economy. If you're graduating from high school or college, a depressed job market looms in front of you. If economics trumps politics, the Millenials could switch.

That is more plausible than it might initially sound. Of the ten states with the lowest unemployment, seven went Republican in the last election. Of the ten states with the largest population growth, again, seven went Republican.

Republicans seem to be winning in states that are growing, where there are jobs, and where the governors seem competent and pragmatic.

Good governance, it turns out, is also very good politics.