Digital

Almost 179,000 USGS historical topographic maps are available free of charge as PDF documents.
That depends on what kind of reprojection you want to do. In some cases, if you want to reproject from one datum to another (specifically NAD 27 to NAD 83, or NAD 83 to NAD 27), a simple x-y shift will suffice.
Yes, customers will need to acquire at least 2 consecutive digital images from the same roll and then create transparencies or contact prints to view them with a stereoscope.
A feature is something shown on a map, and it has characteristics or properties, which can be represented in feature-based Digital Line Graph (DLG) data using attributes and values.
Yes.  Scanning of the EROS film archives is following a plan to capture images from rolls at risk of decay from vinegar syndrome. Science requirements are also reviewed on a regular basis, but a formal, on-line schedule is not available at this time.
Current US Topo maps and maps from the Historical Topographic Map Collection (HTMC) can be downloaded as PDF documents free of charge fr
After the completion of the original 7.5-minute map series in 1992, the USGS mapping program focused on creating national geographic information system (GIS) databases.
Geographically, and as a general reference, the United States (short form of the official name, United States of America) includes all areas considered under the sovereignty of the United States, but does not include leased areas.