On a cross-country trip in 1977 I stopped at a Dairy Queen. When I asked for a root beer float, the woman behind the counter didn't know what I was talking about. They had root beer. They had ice cream. She'd never heard of combining them. "Where you from?", she asked.
I haven't been in Texas (or a Dairy Queen) since, so could someone who has tell me; is this a real cultural quirk, or was she an isolated case?