In 1977, Massimo Vignelli designed the Unigrid System for the National Park Service. The module grid system sized at ISO A2 (16.5? × 23.4?or 420mm × 594mm) allowed the NPS to created brochures in ten basic formats and to keep a consistent, recognizable structure across all it’s materials. Not to mention how economical the system has been for them. The grid features a black bar at the top and bottom with text set in Helvetica in the header bar.

It’s pretty incredible how the Unigrid is still in use today. It just goes to shows how flexible a grid system can be when properly designed.

Issue Journal has an in-depth article on the Unigrid and you can see the grid in action in this Flick group. Also, check out this larger scale redraw of the grid.