According the a Zogby telephone poll from last week, “voters with active passports prefer Kerry 58% to 35%, while those without a passport are for Bush 48% to 39%.”
Perhaps there’s some subtle interpretations of this finding: maybe passport holders are more common along the Canadian Border, and states like Washington, Minnesota, and Maine tend to be more Democratic. Holding a passport is presumably correlated with income and immigrant status.
But my guess is that were you to carefully control for all the relevant background characteristics, the straightforward interpretation would turn out to be right. People who are more familiar with other countries and are less provincial, are naturally more aware of how Bush is destroying America’s reputation, alliances, and influence abroad. And so they’re more likely to support Kerry.