The DLG data files derived from the 1:2,000,000-scale maps contain selected base categories of cartographic data in digital
form. The data files are derived from the sectional maps of the 1970 National Atlas of the United States of America. The Boundaries
category includes boundary information collected in two separate subcategories: (1) Political Boundaries and (2) Administrative
Boundaries. The Hydrography data includes data in three separate subcategories: (1) Streams, (2) Water Bodies, and (3) Hypsography
(Continental Divide only). The Transportation category of data includes major transportation systems collected in three separate
subcategories: (1) Roads and Trails, (2) Railroads, and (3) Cultural Features (airports and Alaska pipeline). <br /> <br />