You almost can't seem to find a tutorial that doesn't use gaussian blur. Of course, it blurs surrounding pixels so they bend together more, causing a de-focusing effect.
I have landed an airplane in 2 states:
I have played a round of golf in 5 states:
I know I have been in (not just layovers) 30 states:
(http://www.epgsoft.com/VisitedStatesMap/)