The 1:100,000-scale Digital Line Graph (DLG) data files are digital representations of cartographic information. Data files of topographic and planimetric map features are derived from cartographic source materials using manual and automated digitizing methods.
Intermediate or 100,000-scale DLG data are derived from U.S. Geological Survey (USGS) 1:100,000-scale 30- by 60-minute quadrangle maps. If these maps are not available, Bureau of Land Management planimetric maps at a scale of 1:100,000 are used. The 1:100,000-scale DLG data distributed by the USGS are in the DLG-Level 3 (DLG-3) format. A DLG-3 file contains a full range of attribute codes, has full topological structuring, and has passed certain quality-control checks.
For information on how to import these DLGs into ArcInfo, see the AML entitled Digial Line Graphs.