NEWS NOTES ON SUSTAINABLE WATER RESOURCESDigital Line Graphshttps://www.usgs.gov/centers/eros/science/usgs-eros-archive-digital-line-graphs-dlgs...
Published on by Tim Smith, Employee at Retiree & P/T Consultant
Digital Line Graphs
https://www.usgs.gov/centers/eros/science/usgs-eros-archive-digital-line-graphs-dlgs-intermediate-scale?qt-science_center_objects=0#qt-science_center_objects
Digital Line Graphs (DLGs) are digital vector representations of cartographic information derived from USGS maps and related sources.
Intermediate-Scale (1:100,000-scale) DLGs are derived from USGS 30- by 60-minute quadrangle maps and are sold in 30- by 30-minute units that correspond to the east or west half of the topographic quadrangle maps. Each 30-minute unit is produced and distributed as four 15- by 15-minute cells. They are cast to the UTM projection system and are referenced to either NAD27 or NAD83.
Depending on scale, the following layers (or categories of feature type) are available:
Layer Feature Type
Public Land Survey System (PLSS) Township, range, and section lines
Boundaries (BD) State, county, city, and other national and State lands such as forests and parks
Transportation (TR) Roads and trails, railroads, pipelines, and transmission lines
Hydrography (HY) Flowing water, standing water, and wetlands
Hypsography (HP) Contours and supplementary spot elevations
Non-vegetative features (NV) Glacial moraine, lava, sand, and gravel
Survey control and markers (SM) Horizontal and vertical monuments (third order or better)
Man-made features (MS) Cultural features, such as buildings, not collected in other data categories
Vegetative surface cover (SC) Woods, scrub, orchards, and vineyards