How does LivingSocial know where I live?

I used to live in Nashville, TN, and all the time the ads would pop up from LivingSocial offering coupons and savings in Nashville. I just assumed it was because Nashville is a populous area, I never really thought much of it. A few weeks ago I relocated to Waco, Texas, and know the ads are offering saving in Waco. How do they know where I live? It's just kind of creepy, like they're stalking me or something. I know they're not, but it's still weird.