Most Americans prefer to huddle together around urban areas, which raises all sorts of problems for map-based visualizations. Coloring regions according to a data value, known as a choropleth map, leaves the map maker beholden to arbitrary political boundaries and, at the county level, pixel-wide polygons in parts of the Northeast. Many publications prefer to place dots proportional in area to the data values over the center of each county, which inevitably produces overlapping circles in these same congested regions. Here's a particularly atrocious example of that strategy I once made at Slate:
Wikipedia contains all sorts of treasures in its edit histories. (The revisions for Jesus are particularly bountiful.) During the later stages of the 2012 Republican primary, I monitored the pages for the four remaining candidates and put together this feature for Yahoo News.