Another Wikipedia map (don’t worry, they won’t all be from there), showing battles of the American Civil War, based on National Park Service data:
Amazingly enough, it turns out that the red-coded counties, coded for “Eastern Theater,” are, in fact all in the east! The color coding has no particular use here, except to show you the difference between the NPS-defined theaters of the war. Why not just draw a border around the zones, so that you don’t need a confusing rainbow of colors to tell you roughly nothing that isn’t apparent by looking at where the filled-in counties are?
Also, why is “Mult. Years” the darkest color? This map’s color scheme suggests that “darker is later” – 1863 is darker than 1861. Making a county that saw battles in multiple years (about half of the ones on the map) even darker than the color for 1865 makes it seem like they were fighting the war there well into the 1870s. A media conspiracy has kept it secret.
Quick tip: Let’s say you’re making a map of something that happened, say, 140+ years ago. Using modern county and state borders might be ill-advised.
It looks like the US is tilted backwards. Maybe it’s a commentary by the author – “Look! The US is falling over…a house divided cannot stand!” Actually, what probably happened is they used a sinusoidal projection, which is good for showing the whole world at times, but not so good for showing one country at high latitudes.
One Nice Thing: The color scheme for the years within each theater makes some level of sense – the colors are arranged in a light-to-dark pattern as the years go on. Excepting, of course, the color for “Mult. Years.” Good cartographic sense.