King County, Texas has seen the biggest shift in political preferences of all US counties since 1960 according to WaPo; but as io9's Mark Strauss notes reveal that during the last two decades, this is not unusual - an increasing number of Americans have chosen to veer Right or Left in their political orientation - with almost no center ground. That trend becomes especially apparent when looking at U.S. election results, county-by-county, since 1960.
As WaPo reports,
We also identified the two counties that changed the most and least between 1960 and 2012. Wyoming County, N.Y., has voted 30-plus percentage points more Republican than the rest of the country in basically every election since John Kennedy first won. King County, Tex., however, has gotten remarkably more conservative.
This is how every single county in the United States has voted vs. the national average since 1960.
The redder the red, the more Republican the county voted than the rest of the country. The bluer the blue, the more Democratic it voted.