Digital Line Graph Map

http://proceedings.esri.com/library/userconf/proc00/professional/papers/pap691/p691.htm
The image above is an example of a digital line graph map. It is a type of USGS topographic map, meaning it is georectified and derived from aerial photography. DLGs are used to show an areas topography and many other features, such as hydrology, and urban features like highways, telephone lines, and utility lines. DLGs different though, as data on them are presented as digital vector data. Map features are shown as lines, points, and areas and polygons.The map above shows streets and highways and uses color to distinguish the major roads.