GIS6005: Color Choropleth

 

    The linear and adjusted color ramps both worked, but they behaved differently when compared to the ColorBrewer ramp. The linear ramp showed even steps in the RGB values, but the darker colors were still hard to tell apart. This made the lower end of the ramp feel a little flat. The adjusted ramp fixed this by using bigger jumps in the darker colors and smaller jumps in the lighter colors. This made the whole ramp easier to read, especially in the first few classes.

    When I compared both ramps to the ColorBrewer version, it was clear that ColorBrewer still looked smoother and more balanced. ColorBrewer ramps seem to be designed so that each step is easy to see, and the colors change at a steady pace. My adjusted ramp came closer to that look, but the ColorBrewer ramp still had the most even and natural progression overall.

    For this choropleth map of population change in Colorado, I used a diverging color scheme and a Natural Breaks (Jenks) classification to show both population gains and losses clearly. Positive percent change values are shown in blue and negative values in red, with the classes arranged so that growth appears at the top of the legend and decline at the bottom. I rounded the class break values to one decimal place to keep the labels easy to read and consistent. The diverging scheme helps emphasize the contrast between counties that experienced growth and those that lost population during the 2010 to 2014 period, making the overall pattern easier to interpret.