SDTS line (DLG) data is available from the following U.S. Geological Survey (USGS) Web site:
USGS SDTS-DLG data
The Master Data Dictionary for SDTS data can be downloaded from the same location. The Master Data Dictionary needs to be stored in a folder within the directory containing the data to be converted, and it must be named MASTERDD.
Please reference the article in the Related Information section, which outlines the correct procedure for unzipping the .tar.gz files containing the SDTS data.