Digital Line Graph - Large Scale

Digital line graph (DLG) data are digital representations of cartographic information. DLGs of map features are converted to digital form from maps and related sources. Large-scale DLG data are derived from USGS 1: 20,000-, 1: 24,000-, and 1: 25,000-scale 7.5-minute topographic quadrangle maps and are available in nine categories:
(1) hypsography, (2) hydrography, (3) vegetative surface cover, (4) non-vegetative features, (5) boundaries, (6) survey control and markers, (7) transportation, (8) manmade features, and (9) Public Land Survey System. All DLG data distributed by the USGS are DLG - Level 3
(DLG-3), which means the data contain a full range of attribute codes, have full topological structuring, and have passed certain quality-control checks.