OK, I guess "culture" can mean any of these:

historical signficance
sophistication of the people
sophistication of the sights, events, attractions
etc.

At least in many other countries, if the people aren't very sophisticated, the location has significance. Or if the place isn't that significant, the people balance it by being interesting (maybe just by being a foreigner, you can think that this is true).

But I can't think of too many US places that rank well by any of these criteria -- there's just too much suburban middle-america wasteland that swamps any faint signal. And then there's that whole part of the US that's called the midwest...

Chicago is good, maybe you can help me name some others?

And, no, "shopping" in a city to me does not really constitute culture...