A federal judge on Tuesday struck down Pennsylvania's ban on same sex marriage, making it the 19th state in which gay people are now free to marry. What do those 19 states (plus the District of Columbia) have in common? Every one of them went for President Obama in both the 2008 and 2012 elections.

For all of the momentum that efforts to legalize same sex marriage have -- nine states have overturned bans since the Supreme Court gave federal recognition to same sex couples last June -- the states in which those efforts have succeeded remain, almost exclusively, Democratic strongholds. With the exceptions of Iowa and New Hampshire -- and, maybe, Pennsylvania -- none of the remaining 16 (or 17) states where gay marriage is legal are even marginally competitive at the presidential level.

Here's our awesome map on the status of gay marriage across the country.

And here's the 2012 election results.

What's clear from looking at the two maps is that the true tipping point on gay marriage legalization is in Republican strongholds like Texas, Utah, Idaho and Oklahoma where bans have been ruled unconstitutional but an appeals process is underway.

We might not have to wait all that long to see whether the momentum in blue states will extend to areas less friendly toward Democrats. The 10th U.S. Circuit Court of Appeals heard arguments on Utah's law in April and a ruling is expected some time in the near future. That same court heard arguments on the Oklahoma case in December 2013. In Arkansas on Friday, the state Supreme Court stayed a lower court decision that overturned the state's ban on gay marriage.

Now, it's important to separate the ongoing legal wrangling over gay marriage from the political fight on the issue, which, as we have written before, is effectively over. Support for gay marriage continues to reach historical highs -- as it did in new Gallup polling released Wednesday.

Public opinion is moving rapidly on the issue. The legal process moves slower but the key lies not in the blue states that have legalized it to date but in the red states that might follow suit soon.