1. A method of distributing map data from a map server to a wireless communications device, the method comprising: obtaining vector map data in response to a request for map data received at the map server from the wireless communications device; generating a bitmap array that is a low-resolution representation of the vector map data for a particular location specified in the request; computing attributes of the bitmap array to determine which polyline map features are too proximate to other polyline map features; simplifying the map data by omitting any polyline map features that are too proximate to the other polyline map features to thereby provide simplified map data; and transmitting to the wireless communications device only the simplified map data for the polyline map features to be retained.