How many maps are on each CD? How many CDs does it take to cover a state?
In our USGS Topographic Series (our largest CD series), we try to cover each state in as few CDs as possible. This means we try to fit as many maps as we can on each CD. Our sophisticated file compression method lets us fit 150- 350 maps on each CD. Each CD’s map count depends in part on the kind of terrain represented, and the type of map used to cover the area. For example, maps in desert areas may contain fewer colors and details, and often these image files take up less space. By contrast, many coastal areas are covered by orthophotomaps, which are generated from satellite and aerial photographs, and typically contain many different colors and patterns to represent subtle terrain differences. These map images generally take up more file space on a CD. Smaller states (like most of the New England states) can fit on one CD. A few other examples: Georgia, Illinois, and New York are five-CD states, and Texas contains 17 CDs. Our Take a Hike CD Series focuses on specific recreational ar
