Search Results: starting a conversation with a girl

I came to US not long ago, and I'm not sure if this is an indication of interest here in US. For the last few months, I've been going to nightclubs and whenever I would find a girl hot she would come close to me and would start dancing while facing her butt to me. They're usually 2 to 3 inches away from me, but since I'm not sure whether they're interested I'd do nothing. They usually leave after 2 to 3 mins but in some cases they continue (those not very hot). Well, I wouldn't ask this question if it hadn't been that frequent so any inputs from girls would be appreciated.
In the Netherlands, and in most nordic countries for that matter, girls make it clear that they like you. Often, they are the ones starting the conversation. Smiling and long eye contacts are strong indications there. However, I don't find such behaviors in the nightclubs in US. I see a girl, and I if like her I keep looking. Either nothing from their side, or just coming close and dancing; very little eye contact, and often no smiles.