What is the source map scale for the data?
The source map scale for most of the data on the CDs is 1:24,000 scale (1″=2,000′), matching the scale of the 7 Minute USGS Topographic maps. This means that most of the data on the CDs was collected, compiled and mapped at the same scale as the Topos, usually with the Topos as a base reference. The source map scale also corresponds to the most detailed (largest) map scale appropriate for displaying and printing out the data on the CDs. Zooming in beyond the source map scale is comparable to using a photocopy machine to enlarge portions of a published map – the blowup photocopy may be easier to read but it is no more accurate than the original map. The Data Guides in the GIS Catalog document the source map scale for all data on the CDs.
