In US cities, the densest lines will have one stop per "block" — and that's frequently a regular tenth or eighth of a mile (and more regular as you move towards

In US cities, the densest lines will have one stop per "block" — and that's frequently a regular tenth or eighth of a mile (and more regular as you move towards the newer cities in the west). So you'll typically find minimum distances of 160m or 200m and then multiples of those for express lines or less dense areas.