Blue and red metros aren't evenly distributed. The coasts cluster hard left, the interior goes red, and the sunbelt swings depend on which city you're in. Most Republican: • Provo (71%) • Knoxville (67%) • Greenville (67%) • Chattanooga (65%) • Tulsa (65%) Most Democrat: • San Francisco (77%) • Madison (72%) • Durham (71%) • Washington DC (71%) • San Jose (70%) The polarization is geographic and structural, not random.