A Digital Line Graph (DLG) is a cartographic map feature represented in digital vector form that is distributed by the U.S. Geological Survey (USGS). DLGs are collected from USGS maps and are distributed in large-, intermediate- and small-scale with up to nine different categories of features, depending on the scale. They come in optional and Spatial Data Transfer Standard (SDTS) format and are topologically structured for use in mapping and geographic information system (GIS) applications.