I downloaded hypsography (topo lines) in DLG (Digital Line Graph) format. The file came from OGRIP, although it originally came from USGS. According to Wikipedia, DLG files are
topologically structured for use in mapping and geographic information system (GIS) applications.
However, when I try to load the .dlg file into QGIS, I get an error message:
Invalid Data Source: C:/Users/.../cl303ohy.dlg is not a valid or recognized data source.
Searching for how to load a DLG file into QGIS doesn't yield any helpful results. Apparently 'dlg' is used in the python coding for creating or loading a plugin, so all the search results discuss plugins.
How can I use a DLG file in QGIS?