GC Insights: Choosing the right map projection, and what it means for scale bars and north arrows

Abstract. Map projection choice is usually left to software defaults, yet it determines whether spatial patterns are shown faithfully or systematically distorted. Because every projection trades area, shape, distance, and direction differently, the validity of two common map elements, the scale bar and the north arrow, depends entirely on the projection chosen. A survey of 299 maps drawn at random from a frame of 27 geoscience journals finds that 1.7 % name their projection, 44 % give no way to determine it, and only 16 % draw a graticule, the one device that shows the geometry rather than approximating it. This Insight argues that projection should be a deliberate, purpose-driven choice, and that journals should require authors to declare the coordinate reference system in figure captions.