Beyond party the greatest indicator we're finding demographically for people being 'birthers' is what type of community they live in- it's very much a rural phenomenon.
In North Carolina 29% of the overall population describes where they live as rural, but 43% of the birthers do. In Virginia 24% of the overall population describes where they live as rural, while 33% of the birthers fall into that category.
It's not just that rural voters are more likely to be Republicans. For instance in North Carolina 64% of rural Republicans think he was not born in the US, compared to 47% of Republicans overall. 20% of rural Democrats think he wasn't born in the US, compared to 12% of all Democrats.
That same trend holds in Virginia where 53% of rural Republicans think Obama was not born in the US, compared to 41% of all Republicans.
When we do this poll in Colorado (assuming it holds its lead) we'll also break it down by income and education level to see how strong the trends are on those fronts.