Slide Image: A three-dimensional map visualization of the northern Midwest United States looking north toward Chicago and the Great Lakes showing the high voltage power grid. Lines on the ground composed of a collection of arrow heads represent high voltage transmission lines going across the land. The amount of electric power flowing on each line is represented by the size and proximity of the arrows. Thin vertical cylinders of different heights are in many locations on the map and indicate the relative amounts of power being produced by the various electric generators in the power grid and the amount of reserve generation available at the generators.

Credit: Tom Overbye, University of Illinois at Urbana Champaign