A system and method are disclosed for providing geographic data to mobile units from a remotely located navigation-services provider. When a mobile unit requests route information, the navigation-services provider transmits an initial set of geographic data representing an area around a current position of the mobile unit. The navigation-services provider calculates a route to the destination and then identifies an intermediate exit point along the route that is located within the initial set of data. The mobile unit calculates an initial portion of the route to the intermediate exit point. The navigation-services provider determines a list of geographic-data groups needed to represent the remainder of the route and transmits this list to the mobile unit. Each geographic-data group is transmitted to the mobile unit along with an intermediate exit point. Using the received data, the mobile unit provides route guidance to a local end user.