EROS has digitized over 6.4 million frames of aerial film creating medium-resolution digital images (400dpi) and associated browse images for on-line viewing.
No. A photographic enlargement only appears to show more detail than a 9-by-9 inch photograph. Photographic resolution (or image resolution) deteriorates with each enlargement factor.
YES, Visit our National Geospatial Program page or call 1-888-ASK-USGS for our information package on digital cartographic data. 
UTM coordinates are measured on the map by subdividing the 1000 meter grid squares into tenths or hundredths. This will narrow down the coordinate to a 100 or 10 meter square.
Current US Topo maps, and maps of the Historical Topographic Map Collection (HTMC). are published as PDF documents that can be downloaded free of ch
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.
Generally, for the conterminous United States, the North American Datum (NAD) shift amounts to about 210 meters. This shift occurs because of the change in shape of the spheroid used to define the datum.
It will probably take approximately 5 years to digitize the archive. A priority scheme is being developed and will be made available to the public at a later date.
The online version of the National Atlas (officially known as the 1997-2014 Edition of the National Atlas of the United States), formerly at, was removed from service on September 30, 2014.
The public may download digital aerial photography products at no cost from the Earth Resources Observation and Scien