I've been charged with creating a population density map similar to this one: I'm having trouble figuring out how the population density is displayed on this map. It doesn't appear to be by population/square mile by census block, but by something else. How did the creator of this map create the polygons that are irregular in shape and varying intensities? It's almost like a dissolve was done on the layer? Here's my map of population/square mile by census block: Any advice on how to achieve the look of the first map? Thanks for any input.