In northern Colombia, in the unsettled outskirts of the city of Valledupar, stand parallel rows of newly planted cañaguate trees, the kind you expect to see lining an important road. Except there are no roads in sight, just the young trees. They’re leafy evidence of an urban-planning initiative that’s all too rare. With foresight, Valledupar is acquiring rights of way to build roads that it will need as it expands. The trees, which produce profuse yellow flowers in the dry season, are essentially watch-this-space advertising. It’s cheaper and easier to stake out the roads’ routes now than it will be after the sprawl occurs.