In your city, how many users are iPhone, Android, Blackberry? Twitter use has revealed geographic usage patterns The statistician in me always questions this though. Maybe Blackberry & Android users are less likely to use twitter? (of my extended family, who has ~ 2 iPhones & 5 android – none of us tweet from our phones) However, it’s better than nothing. Here’s the city of Calgary:
https://www.mapbox.com/labs/twitter-gnip/brands/#11/51.0120/-114.1734