The 1:2,000,000-scale Digital Line Graph (DLG) data files include information of planimetric base categories, such as transportation, hydrography and boundaries for the entire United States. The term DLG is used by the USGS to describe map data sets in vector form.
The DLG files were created by manually digitizing the 1:2,000,000-scale sectional maps of the National Atlas of the United States of America. Originally, three levels of DLG data (DLG-1, DLG-2 and DLG-3) were defined. The DLG-3 has the most accurate positional control and has been topologically structured for use in mapping and GIS applications. DLG-3 files are the only levels distributed to the user community.
For information on how to import these DLGs into ArcInfo, see the AML entitled Digial Line Graphs.