The U.S. 2012 Elections County by County

2012 Presidential results by county for 48 contiguous states; blue = Obama, red = Romney, purple = percentages of each

The final U.S. electoral map doesn't reflect the U.S. popular vote with precision, though it is a crude guide to which parts of the country are more liberal and which more conservative. A more refined approach, if one cares about the demographics of voters, is to select hue by percentage of vote and look at outcomes at the county rather than state level. One then gets a fairly clear geographic view of trends.

And even more precise approach is then to weight the counties by population. The size of a county in the U.S. is a somewhat arbitrary measure, so weighting by population seems clearer. The problem is that it so distorts geography that the trends are not particularly sensible. And even better approach, not that I've done it, would be to show population weight by color intensity (tinting areas by lower population). Anyway, Mark Newman, the Paul Dirac Professor of Physics and the University of Michigan, has generated the county-by-county population weighted cartograms and a host of related maps.

As above, weighted by population