Thirty-two states would support same-sex marriage in a popular vote by the year 2016, he writes in a recent blog post. "And by 2020, voters in 44 states would do so, assuming that same-sex marriage continues to gain support at roughly its previous rate."
The six states left out? South Carolina, Arkansas, Georgia, Louisiana, Alabama and Mississippi, according to his analysis. With Mississippi being last.
I recently spent some time in that state, which passed a constitutional amendment banning same-sex marriage by a majority vote of 86%. In states like that, gay people find it difficult in some communities just to exist, much less hold commitment ceremonies.
I met gay kids who had been harassed at school; a couple that keep a security camera on their porch; and a man who says he was fired because of his sexual orientation. (That's legal in Mississippi and 28 other states, by the way, and it's something no one's talking about.)
The conversation is changing -- there are plenty of proud, brave and openly gay people living in the Deep South -- but it's happening at an uneven clip.
And these delays matter for real people.
In Mississippi, I met folks like L.B. and Sara Bell, who are legally married in Connecticut but don't get any of the rights that go with that partnership in the Hospitality State. They told me they would like to start a family but worry about both of them getting custody, since Mississippi bans adoption by same-sex parents. Sara, who would like to carry the child, is 31. If same-sex marriage isn't legalized until, say, 2030, she would be 48.
It would be nice to overlook this mushy, awkward middle period -- our county's pimply adolescence on gay rights -- and jump straight to an all-inclusive future.
But these teenage years matter. They affect how millions of Americans live today. And the transition could also affect what type of nation we become. Let's hope they go by quickly.