Digital line graph

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.

DLGs are distributed at three different scales: large-scale, which normally correspond to the USGS 7.5- by 7.5-minute, 1:24,000 and 1:25,000-scale topographic quadrangle map series, 1:63,360-scale for Alaska and 1:30,000-scale for Puerto Rico; intermediate scale, which are derived from the USGS 30- by 60-minute, 1:100,000-scale map series; and small-scale, which are derived from the USGS 1:2,000,000-scale sectional maps of the National Atlas of the United States.

Small-scale DLGs are sold in state units and are cast on either the Albers equal-area conic projection system or the geographic coordinate system of latitude and longitude, depending on the distribution format.

USGS DLGs are topologically structured for use in mapping and geographic information system (GIS) applications.

Nine different categories of features, or layers, are available in DLGs: Public Land Survey System (PLSS), Boundaries (BD), Transportation (TR), Hydrography (HY), Hypsography (HP), Non-vegetative features (NV), Survey control and markers (SM), Man-made features (MS) and Vegetative surface cover (SC).