There are ways to color the areas behind the plot markers in a gplot (using annotate). And you could do some calculations on the data to do summary counts of the number of obsns/markers in each area, and color the areas accordingly. I don't have an example that does that 'exact' thing, but here's one that is close: http://robslink.com/SAS/democd22/heatmap.htm http://robslink.com/SAS/democd22/heatmap_info.htm ... View more