Sid Meier’s Railroads! is a PC game that is approaching 20 years old, yet it retains an active modding community to this day. This website documents the custom maps that have been uploaded to the Internet Archive and makes them available for easy browsing and downloading. The map data are pulled directly from the Internet Archive using an open-source program that I run periodically as more maps become available.
Be sure to also check out the official game manual and strategy guide, which are also available on the Internet Archive.