How to make beautiful borderless geographic thematic/heatmaps with weighted (survey) data in R, probably using spatial smoothing on point observations

Question

Ever since Joshua Katz published these dialect maps that you can find all over the web using harvard\'s dialect survey, I have been trying to copy and generalize his methods.. b

Answer 1

this is my final answer, regis

http://www.asdfree.com/2014/12/maps-and-art-of-survey-weighted.html