Historical Topographic Maps

The USGS completed the primary topographic map series of the conterminous United States at 1:24,000 in 1992. Revisions were made until 2006. Alaska, Hawaii, Puerto Rico, and Trust Territories were completed earlier and were done at other scales.
Georeferencing means that the internal coordinate system of a map or aerial photo image can be related to a ground system of geographic coordinates.
Not yet. Once available, these deliveries will be handled the same way as bulk deliveries for US Topo and historic maps in GeoPDF. Check this FAQ periodically for updates. 
No. US Topo maps are delivered as multi-layered GeoPDF files and are not well represented as a single layer GeoTIFF image. We are investigating companion US Topo products for users of Geographic Information System software.
No. The primary goal of the HTMC project is to preserve, as completely as possible, the set of historic topographic maps in their original form. Removing the collar would separate the map from some of its history and metadata. 
GeoPDF maps are ideal for users who simply want to view or print a map.  Free Adobe Reader software enables this basic functionality.
The Historic Topographic  Map Collection concentrates on obtaining quadrangles with scales of 1:250,000 and larger; a statistical breakdown is here.
USGS Digital Raster Graphics (DRGs) were created in the period 1995-2000. They were 250 dots-per-inch scanned images of what were then the most current editions of topographic maps (approximately 58,000 maps).
GeoTIFFs preserve the original paper map’s datum and projection, just as GeoPDFs do. Learn More: USGS Digital Raster Graphics