Flavored popcorn is big in Singapore. I would agree with those who say it is not so much in the US - in fact, it wasn't even until I studied abroad in the UK that I had ever encountered the idea that movie theater popcorn could be sweet rather than salty, although I suppose I'd seen it at carnivals or that sort of thing and did encounter those bags of store bought cheese-dusted popcorn as a child. But I suppose there's at least some evidence that the nexus of this flavored popcorn thing is in Chicago? kalimac mentions above his encounters in the Chicago airport, and there's this store in Singapore which seems to be "a Chicago tradition since 1949." There is evidently a single branch in New York City, in Penn Station, which contrasts with the 6 branches in Singapore and possibly helps to explain why, despite frequenting Penn Station when I am in NYC, I think of this as being far more common in Singapore.