The palette
Chicago asks for a binary drawing: the dense ink of the grid, and one great blue. The lake should hold the eastern quarter of the sheet in a full, calm value, the shore of parks a narrow green fringe between the water and the weave. The river and the canal will take the same blue as the lake: a map has a single ink for all its water. To keep the inverted Y legible in the mass, move the colour of the streets away from that blue, in hue rather than in value: that is what the brick of our poster does.