1. An apparatus for map zooming, comprising instructions stored in a memory that when executed by a processor render a zoom bar, comprising: a plurality of map scale hash marks arranged along an axis of the zoom bar and indicative of a map scale range of a geographic map, the plurality of map scale hash marks comprising: a first map scale hash mark representative of a first map scale; a second map scale hash mark offset along the zoom bar axis from the first map scale hash mark and representative of a second map scale; and a map transformation hash mark located between the first and second map scale hash marks and representative of a transformation of the geographic map from a first map data set defined with reference to the first map scale to a second map data set defined with reference to the second map scale; and a map zoom bar indicator located relative to the first and second map scale hash marks and corresponding current map display scale and a zoom level of the geographic map wherein the geographic map includes the first map data set when the map zoom bar indicator is located on one side of the map transformation hash mark along the zoom bar axis and the geographic map includes the second map data set when the map zoom bar indicator is located on the other side of the map transformation hash mark opposing the one side.