Does equality breed conservatism?

There’s an article in the New York Times today. Most of it is to US-centric to be of great relevance here, but this paragraph made me think:

Measured by money income, Washington qualifies as one the most unequal cities in the United States. Yet these two very different halves of a single city do share at least one thing. They vote the same way: Democratic. And in this, we are not alone. As a general rule, the more unequal a place is, the more Democratic; the more equal, the more Republican. The gap between rich and poor in Washington is nearly twice as great as in strongly Republican Charlotte, N.C.; and more than twice as great as in Republican-leaning Phoenix, Fort Worth, Indianapolis and Anaheim.

If this is true, is this because people in equal places want to become unequal, and vice versa?

I do wonder whether it’s universally applicable, though. Scandinavians don’t seem to be going for conservative parties in droves, for instance.