This is an isochronic map – isochrones being lines joining points accessible in the same amount of time – and it tells a story about how travel was changing. You can get anywhere in the dark-pink section in the middle within five days – to the Azores in the west and the Russian city of Perm in the east. No surprises there: you’re just not going very far. Beyond that, things get a little more interesting. Within five to ten days, you can get as far as Winnipeg or the Blue Pearl of Siberia, Lake Baikal. It takes as much as 20 days to get to Tashkent, which is closer than either, or Honolulu, which is much farther away. In some places, a colour sweeps across a landmass, as pink sweeps across the eastern United States or orange across India. In others, you reach a barrier of blue not far inland, as in Africa and South America. What explains the difference? Railways.