Cran's 1889 Rail Road Map is a large file, as any historical map needs to be; if it is to be readable. Please be prepared for a long load time when you click on the Map Link. Most are familiar with paper maps, they are printed intentionally large to cover a large aria yet remain readable. The average printed map would cover the top of an average table. Thus a readable digitized file can not be small, as can be seen, as shown in the illustration here.
A little about George F Cram.
The Cram 1889 Rail Road Map at Stanford University Library. Large file warning.