Here is a map of the main railway routes of Europe in 1862. But, the thicker the line; the more people and goods it carries…So, not just a railway map; but a diagram of trade relations, economy, and association, across the continent.
This idea in graphic and information design was developed by the French engineer, CJ Minard.
You can see, straight away, that the UK has a much more evenly developed network of routes and carries much more railway traffic.