Digital maps are generally the norm these days but the preservation of older digital maps presents a problem. Jani Stenvall has written a short paper on the subject that might be of interest. The paper provides a broad overview of some of the issues rather than providing a specific set ofd solutions.

From the paper: “The wide range of different digital products and their special characteristics impose a great new challenge to libraries. The file formats, software needed to render the publication, and hardware requirements are developing rapidly and this means obsolete environments for older digital materials. The fast moving computer technology is providing us new updated software and 'improvements' all the time. This development is leaving a trace of obsolete systems, formats and above all those important documents that we used in those obsolete environments. The computer industry that is creating our digital world today is also erasing our digital yesterday.”

By way of Great Map