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Product Description
Digital Line Graphs (DLGs) are
digital vector representations of cartographic information derived from USGS maps and related sources.
Depending on scale, the following layers (or categories of feature type) may be available:
| Layer |
Feature Type |
| Public Land Survey System (PLSS) |
Township, range, and section lines |
| Boundaries |
State, county, city, and other national and State lands such as forests and
parks |
| Transportation |
Roads and trails, railroads, pipelines and transmission lines |
| Hydrography |
Flowing water, standing water, and wetlands |
| Hypsography |
Contours and supplementary spot elevations |
| Non-vegetative features |
Glacial moraine, lava, sand, and gravel |
| Survey control and markers |
Horizontal and vertical monuments (third order or better) |
| Manmade features |
Cultural features, such as building, not collected in other data categories |
| Vegetative surface cover |
Woods, scrub, orchards, and vineyards |
DLGs are available in Optional format, written as ANSI-standard ASCII characters in fixed-block format.
The USGS produces three primary types of DLG data:
- Large-Scale (7.5-minute) DLGs correspond to the USGS 1:20,000-, 1:24,000-, and 1:25,000-scale topographic quadrangle maps. They are primarily cast to the Universal Transverse Mercator (UTM) projection system, but some are cast to the State Plane coordinate system. They are referenced to either the North American Datum (NAD) of 1927 (NAD27) or the NAD of 1983 (NAD83). The files are available in Optional and Spatial Data Transfer Standard (SDTS) format. Optional format is distributed via File Transfer Protocol (FTP). SDTS format is distributed via FTP download.
- 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. The files are available in Optional and SDTS format. Optional format is distributed via File Transfer Protocol (FTP). SDTS format is distributed via FTP download.
- Small-Scale (1,2,000,000-scale) DLGs are derived from the USGS sectional maps from the U.S. National Atlas. 1:2,000,000 State DLGs contain files that date between 1990 and 1994. The files are organized on a state-by-state basis, and include the conterminous U.S. and Hawaii. Alaska is not available. They are cast to Albers Equal-Area conic projection. 1:2,000,000 State DLGs are available in SDTS format and distributed via FTP download.
Additional Information:
Prices
| Product |
Media |
Price |
| Large-Scale (7.5-minute) DLGs Optional format |
CD, DVD |
$3.00 per file |
| Large-Scale (7.5-minute) DLGs SDTS format |
FTP download |
No charge |
| 1:100,000-Scale DLGs |
FTP download |
No charge |
| 1:100,000-Scale DLGs |
CD, DVD |
$3.00 per file |
| 1:2,000,000 Section DLGs |
FTP download |
No charge |
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Sample Data
A sample Large-scale DLG can be downloaded from USGS Geographic Data Samples.
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