It seems to be mmebership in a demographic. I'd say it's more belief-based than that. 

1. If you prefer the North East over the South you are an elitist.

2. If you root for the Yankees you are an elitist.
3. If you consider yourself an independent politically you are an elitist.
4. If you are picky about grammar "your" an elitist.
5. If you prefer snow skiing to water skiing you are an elitist.
6. If you are a free market capitalist at heart you are an elitist.
7. If you have attended an Ivy League school you are an elitist.
8. If you live in New England by choice you are en elitist.
9. If you have the grossly misbegotten idea that BBQ made in New York is in any way comparable to that of the South you are an elitist.
10. If you ever engaged in a fairly pointless back and forth thread on the Lounge of at least 5 responses each between you and one other poster you are an elitist.
11. If you feel the need to respond to this post you are an elitist's elitist of the elitist elite.