This is a map of median property taxes collected at the county level, averaged over a 5-year period from 2008 to 2012. This data is based on census surveys.
This map was built to generate SVGs which would be further manipulated in Adobe Illustrator, so no CSS is used to apply styles to SVG elements.
This map takes two base colors, a number of predefined scale increments, and a predefined range to generate and apply a limited number of specific colors to each county. In this example, the scale ranges from $0 to $4,000, with $500 increments. So between $0 and $499.99 is the first increment, between $500 and $999.99 the second, etc., until the final increment of $4,000 and above. Light colors correspond to low values, and dark to high values.